DOCUMENT RESUME

ED 402 191 SE 059 486

AUTHOR Horton, Robert L.; And OthersTITLE Rockets Away! A Fun Approach to Exploring the Science

of Rocketry. Teacher's Edition.INSTITUTION National Center for Science Teaching and Learning,

Columbus, OH.; Ohio State Univ., Columbus.Cooperative Extension Service.

SPONS AGENCY Office of Educational Research and Improvement (ED),Washington, DC.

REPORT NO 4-H-501-GPMPUB DATE 94CONTRACT R117Q00062NOTE 61p.

PUB TYPE Guides Classroom Use Teaching Guides (ForTeacher) (052)

EDRS PRICE MF01/PC03 Plus Postage.DESCRIPTORS Aerospace Education; *Engineering; Intermediate

Grades; Junior High Schools; Middle Schools; ScienceActivities; Science Experiments; *Space Sciences

IDENTIFIERS *Rockets

ABSTRACTThis unit is designed to stimulate interest in math,

engineering, aerospace, and physics through the exploration ofrocketry science. It serves as a ready source of information dealingwith the subject of rocketry and provides directions for completing avariety of hands-on rocketry science experiments, including thedesign, construction, and launch of 2-liter bottle rockets. Theteaching outline consists of four parts: introduce new knowledge;summarize learning; bring closure to session; and review previoussession when starting new session. Sections include: Exploring theMotion of Rockets, Building on the Basics, and Let's Get Launching.(JRH)

************************************************************************ Reproductions supplied by EDRS are the best that can be made *

from the original document.***********************************************************************

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roc

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incl

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n an

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r bo

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Wri

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Thi

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it is

des

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stim

ulat

e in

tere

st in

mat

h,en

gine

erin

g, a

eros

pace

, and

phy

sics

thro

ugh

the

expl

o-ra

tion

of r

ocke

try

scie

nce.

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ill s

erve

as

read

y so

urce

of in

form

atio

n de

alin

g w

ith th

e su

bjec

t of

rock

etry

, as

wel

l as

prov

ide

dire

ctio

ns f

or c

ompl

etin

g a

vari

ety

ofha

nds-

on r

ocke

try

scie

nce

expe

rim

ents

. Thi

s in

clud

esth

e de

sign

, con

stru

ctio

n an

d la

unch

of

2-lit

er b

ottle

rock

ets

as d

etai

led

in s

ectio

n th

ree.

The

ben

efit

to u

sing

2-lit

er b

ottle

roc

kets

is th

at th

ere

is n

o ne

ed f

or e

xpen

-si

ve s

olid

roc

ket e

ngin

es, n

or is

ther

e th

e la

rge

inve

stm

ent o

f tim

e in

the

desi

gn a

nd c

onst

ruct

ion

of th

ero

cket

s. I

n ad

ditio

n, 2

-lite

r bo

ttle

rock

ets

can

easi

ly b

em

odif

ied

to a

ccom

mod

ate

a va

riet

y of

exp

erim

ents

, or

toim

prov

e th

eir

over

all p

erfo

rman

ce.

As

you

begi

n ea

ch s

essi

on, b

e su

re to

incl

ude

a pr

oper

intr

oduc

tion

and

disc

ussi

on o

f in

form

atio

n to

be

cove

red.

Thi

s w

ill h

elp

the

clas

s pr

epar

e fo

r th

e le

arni

ng th

at f

ol-

low

s Fo

r be

st r

esul

ts, c

ondu

ct e

xper

imen

ts a

sde

mon

stra

tions

with

gro

up m

embe

rs a

s ac

tive

part

ici-

pant

s. O

r, if

you

wis

h, p

rovi

de a

n op

port

unity

for

gro

upm

embe

rs to

con

duct

exp

erim

ents

on

thei

r ow

n or

inte

ams.

Thi

s is

esp

ecia

lly im

port

ant i

n le

sson

s 2

& 3

whe

regr

oup

mem

bers

con

stru

ct a

nd f

ly e

xper

imen

tal r

ocke

ts.

Onc

e an

act

ivity

is c

ompl

eted

, allo

w ti

me

for

proc

ess-

ing

Use

the

guid

ing

ques

tions

as

prov

ided

to h

elp

grou

pm

embe

rs r

elat

e w

hat t

hey

obse

rved

and

exp

erie

nced

.W

hen

proc

essi

ng a

n ac

tivity

, try

not

to f

ocus

on

answ

ers

bein

g "r

ight

" or

"w

rong

." R

athe

r, a

ccep

t all

answ

ers

as p

os-

sibl

e so

lutio

ns. T

hen,

hel

p th

e gr

oup

see

why

a p

artic

ular

answ

er m

ay b

e m

ore

appr

opri

ate

than

oth

ers,

esp

ecia

lly if

6

the

answ

er y

ou w

ere

look

ing

for

was

not

giv

en.

Plan

on

at le

ast t

wo

hour

s to

com

plet

e se

ssio

ns 1

& 2

.T

his

incl

udes

per

form

ing

all o

f th

e re

com

men

ded

expe

ri-

men

ts a

long

with

tim

e fo

r gr

oup

disc

ussi

on. S

essi

on 3

shou

ld b

e ex

tend

ed o

ver

a lo

nger

per

iod

of ti

me

in o

rder

for

grou

p m

embe

rs to

com

plet

e al

l fiv

e pr

oble

ms.

Tim

epe

rmitt

ing,

you

may

wis

h to

exp

lore

som

e of

the

Dig

ging

Dee

per

and

Goi

ng B

eyon

d ac

tiviti

es in

eac

h le

sson

.

Tea

chin

g O

utlin

e -

The

fol

low

ing

is a

rec

omm

ende

dou

tline

for

con

duct

ing

a se

ries

of

sess

ions

on

this

sub

ject

.In

trod

uce

new

kno

wle

dge

Rel

y he

avily

on

show

ing

rath

er th

an te

lling

. Ref

er to

the

exam

ples

in e

ach

less

on,

or u

se y

our

own

to g

et y

our

mes

sage

acr

oss.

As

you

teac

h, f

ocus

on

impr

ovin

g th

e le

arne

r as

a p

erso

n, a

sw

ell a

s he

lpin

g th

e gr

oup

lear

n ne

w th

ings

.Su

mm

ariz

e L

earn

ing

Hav

e th

e gr

oup

talk

abo

utw

hat t

hey

lear

ned

and

wha

t the

y lik

ed d

oing

. Foc

us o

nth

e po

sitiv

e, e

spec

ially

if th

ings

did

n't w

ork

as y

oupl

anne

d.B

ring

clo

sure

to S

essi

onPr

ovid

e an

ove

rvie

w o

fw

hat w

ill b

e co

vere

d du

ring

the

next

ses

sion

. Try

bui

ld-

ing

exci

tem

ent f

or w

hat's

to c

ome

by g

ivin

g th

e gr

oup

apr

oble

m to

sol

ve o

r m

aybe

eve

n a

ques

tion

to b

e an

-sw

ered

.W

hen

star

ting

next

tim

e .

..

revi

ew p

revi

ous

sess

ion.

Thi

s w

ill h

elp

the

lear

ners

hav

e a

com

mon

sta

rtin

gpl

ace

for

the

curr

ent s

essi

on a

nd le

ad in

to n

ew in

form

a-tio

n.

7

Get

ting

Sta

rted

With

the

Uni

tSt

ep 1

: Obt

ain

the

requ

ired

mat

eria

ls li

sted

for

each

exp

erim

ent.

Whe

n co

nduc

ting

as a

grou

p, p

lan

on h

avin

g le

arne

rs w

ork

in te

ams

of 2

-3 w

hene

ver

poss

ible

. Thi

s w

ill h

elp

cut

dow

n on

the

amou

nt o

f su

pplie

s ne

eded

as

wel

l as

faci

litat

e co

oper

ativ

e le

arni

ng a

mon

ggr

oup

mem

bers

.St

ep 2

: Roc

ketr

y eq

uipm

ent L

esso

n th

ree

is d

e-si

gned

to h

elp

lear

ners

app

ly w

hat t

hey

lear

ned

in th

epr

evio

us tw

o le

sson

s in

a u

niqu

e st

ep-b

y-st

ep p

robl

emso

lvin

g ap

proa

ch. T

his

incl

udes

the

desi

gn, c

onst

ruc-

tion,

and

laun

chin

g of

2-l

iter

bottl

e ro

cket

s. B

e su

re to

phot

ocop

y th

e ap

prop

riat

e pa

ges

from

this

less

on a

nddi

stri

bute

them

to g

roup

mem

bers

. Thi

s le

sson

wor

ksbe

st w

hen

grou

p m

embe

rs c

an w

ork

on th

eir

own

or in

team

s to

des

ign

and

build

thei

r 2-

liter

bot

tle r

ocke

ts.

Step

3: O

ptio

nal C

ompu

ter

Ass

iste

d In

stru

ctio

nFo

r le

arne

rs w

ith a

cces

s to

an

IBM

com

patib

le c

om-

pute

r, a

n op

tiona

l pro

gram

is a

vaila

ble

to te

ach

them

abou

t the

pro

per

desi

gn a

nd f

light

con

figu

ratio

ns o

f 2-

liter

bot

tle r

ocke

ts. T

his

sim

ulat

ion

prog

ram

will

hel

pth

em s

olve

pro

blem

s lik

e de

term

inin

g th

e pr

oper

des

ign

for

a no

se c

one

and

tail

fin,

test

ing

the

prop

er r

atio

be-

twee

n fu

el c

apac

ity a

nd w

ater

pre

ssur

e fo

r m

axim

umra

nge,

or

dete

rmin

ing

the

idea

l wei

ght f

or a

2-l

iter

bottl

ero

cket

.

Thi

s di

sket

te a

lso

cont

ains

a p

rogr

am f

or r

e-co

rdin

g an

d an

alyz

ing

laun

ch d

ata

usin

g 2

liter

bottl

e ro

cket

s. T

his

is a

mus

t for

lear

ners

in-

tere

sted

in p

erfe

ctin

g th

e de

sign

of

thei

r 2

liter

bot

tle r

ocke

t. A

s le

arne

rs e

nter

dat

aba

sed

on th

e am

ount

of

wat

er a

nd p

res-

sure

use

d fo

r ea

ch la

unch

, inc

ludi

ng th

etim

e it

took

fro

m la

unch

to la

ndin

g, th

epr

ogra

m w

ill d

eter

min

e al

titud

e an

d sp

eed

ofth

e ro

cket

as

wel

l as

pred

ict i

deal

wat

er/p

ress

ure

ratio

s fo

r fu

ture

laun

ches

.

8

AW

AY

! (.E

xplo

ring

the

Mot

ion

of R

ocke

ts

4410

71'

11

Roc

ket R

un-D

own

The

sci

ence

of

rock

ets

bega

n w

ith th

e di

s-co

veri

es o

f Is

aac

New

ton.

Roc

kets

rel

y on

the

unba

lanc

ing

of f

orce

sfo

r m

otio

n.R

ocke

ts w

ill s

peed

up

whe

n m

ass

is d

e-cr

ease

d or

thru

st is

incr

ease

d.A

roc

ket's

for

war

d m

otio

n is

a r

eact

ion

toth

e ra

pid

disc

harg

e fr

om it

s en

gine

s.G

ravi

ty is

a f

orce

hel

d co

nsta

nt a

gain

st th

epe

rfor

man

ce o

f ro

cket

s.

Bac

kgro

und

A r

ocke

t in

its s

impl

est f

orm

is a

cha

mbe

r en

clos

ing

a ga

s un

der

pres

sure

. A s

mal

l ope

ning

at o

ne e

nd o

f th

ech

ambe

r al

low

s th

e ga

s to

esc

ape

in o

ne d

irec

tion,

and

in d

oing

so

prov

ides

a th

rust

that

pro

pels

the

rock

et s

ky-

war

d in

the

oppo

site

dir

ectio

n. M

ost h

isto

rian

s be

lieve

that

roc

kets

wer

e in

vent

ed b

y th

e C

hine

se a

roun

d th

e

11th

cen

tury

AD

. The

se e

arly

roc

kets

wer

e us

ed b

y th

eC

hine

se to

rep

el in

vade

rs, s

uch

as th

e M

ongo

ls.

By

the

thir

teen

th c

entu

ry th

e us

e of

roc

kets

had

spre

ad to

the

Mid

dle

Eas

tern

cou

ntri

es w

here

they

wer

ekn

own

as "

Chi

nese

Fir

e A

rrow

s."

The

se e

arly

roc

kets

wer

e lit

tle m

ore

than

tube

s st

uffe

d w

ith g

unpo

wde

r.W

hen

the

gunp

owde

r w

as ig

nite

d, it

exp

lode

d an

d pr

o-du

ced

hot g

asse

s th

at "

push

ed"

the

rock

ets

into

flig

ht.

Eve

ntua

lly, t

he u

se o

f ro

cket

s fo

r bo

th w

arfa

re a

nd e

n-te

rtai

nmen

t spr

ead

wor

ldw

ide.

How

ever

, it h

as b

een

only

sinc

e th

e la

st th

ree

hund

red

year

s th

at r

ocke

t exp

eri-

men

ters

hav

e ac

tual

ly u

nder

stoo

d th

e sc

ient

ific

prin

cipl

es b

ehin

d th

e m

otio

n of

roc

kets

.

Did

you

Kno

w R

ocke

ts w

ere

used

inm

any

battl

es in

clud

ing

one

fam

ous

battl

eag

ains

t the

Uni

ted

Stat

es d

urin

g th

e W

arof

181

2. D

urin

g th

e ba

ttle,

at B

altim

ore'

sFo

rt M

cHen

ry, a

you

ng p

oet n

amed

Fran

cis

Scot

t Key

wat

ched

the

rock

etbo

mba

rdm

ent a

nd w

rote

a p

oem

abo

ut"t

he r

ocke

t's r

ed g

lare

/the

bom

bs b

urst

-in

g in

air

." L

ater

, set

to m

usic

, tha

t poe

mbe

cam

e th

e A

mer

ican

nat

iona

l ant

hem

, The

Sta

r-Sp

angl

ed B

anne

r.

Dis

cuss

ion

Beg

in b

y di

scus

sing

the

mov

emen

t of

obje

cts

both

inth

e at

mos

pher

e an

d in

spa

ce. H

ave

a to

y ro

cket

and

aw

ind-

up b

alsa

woo

d gl

ider

on

hand

to il

lust

rate

key

poin

ts. S

tart

the

grou

p th

inki

ng b

y as

king

the

ques

tion

..

. "H

ow d

oro

cket

s m

ove?

" H

elp

the

grou

p un

ders

tand

10

iiiN

ewto

n's

Firs

t Law

Obj

ects

at r

est w

ill s

tay

at r

est,

orob

ject

s in

mot

ion

will

sta

y in

mot

ion

unle

ss a

cted

upo

n by

an

unba

lanc

ed f

orce

.

guid

ing

ques

tions

to h

elp

grou

p m

embe

rs p

roce

ss th

eir

obse

rvat

ions

as

wel

l as

appl

y w

hat t

hey

lear

ned

to r

eal

life

situ

atio

ns.

Exp

lain

that

dur

ing

a ro

cket

's f

light

. for

ces

beco

me

bala

nced

and

unb

alan

ced

all t

he ti

me.

A s

mal

l mod

elro

cket

sitt

ing

on th

e la

unch

pad

exp

erie

nces

a b

alan

ceof

for

ces.

The

sur

face

of

the

pad

prov

ides

a b

alan

ced

forc

e ag

ains

t the

mas

s of

the

rock

et b

eing

pul

led

dow

nby

gra

vity

. Whe

n th

e en

gine

igni

tes,

its

thru

st u

nbal

ance

the

forc

es, a

llow

ing

the

rock

et to

trav

el u

pwar

d. T

his

thru

st c

ontin

ues

until

the

engi

ne's

fue

l is

exha

uste

d.O

nce

this

occ

urs,

the

rock

et b

ecom

es s

usce

ptib

le to

the

forc

es o

f gr

avity

and

atm

osph

eric

fri

ctio

n. T

hese

unb

al-

ance

d fo

rces

act

upo

n th

e ro

cket

's f

orw

ard

mot

ion

caus

ing

it to

slo

w a

nd e

vent

ually

fal

l bac

k to

ear

th.

that

roc

kets

do

not m

ove

like

conv

entio

nal a

ircr

aft w

hich

pull

them

selv

es a

long

thro

ugh

the

atm

osph

ere.

To

dem

-on

stra

te th

is p

oint

, win

d up

you

r ba

lsa

woo

d gl

ider

and

rele

ase

it sk

ywar

d. P

oint

out

that

the

glid

er s

tays

alo

ft a

slo

ng a

s th

e pr

opel

ler

keep

s tu

rnin

g.C

ompa

re th

is to

the

mov

emen

t of

a ro

cket

. Tie

ast

ring

aro

und

the

mid

sec

tion

of y

our

rock

et a

nd tw

irl i

tov

er y

our

head

. Exp

lain

that

a r

ocke

t's m

ovem

ent i

s no

tca

used

by

the

push

ing

or p

ullin

g of

its

engi

nes

agai

nst

the

atm

osph

ere.

If

this

wer

e th

e ca

se, r

ocke

ts w

ould

be

unab

le to

trav

el th

e ai

rles

s vo

id o

f sp

ace.

Rat

her,

aro

cket

rel

ies

upon

a d

iffe

rent

type

of

"sus

tain

ed f

orce

" to

achi

eve

mot

ion.

In

the

case

of

the

rock

et c

ircl

ing

abov

eyo

ur h

ead,

its

actio

n is

the

resu

lt of

the

mov

emen

t in

your

wri

st. A

s lo

ng a

s yo

ur w

rist

con

tinue

s to

twir

l, th

ero

cket

will

con

tinue

to m

ove.

Exp

lain

that

the

rem

aind

er o

f th

e le

sson

will

foc

uson

hel

ping

the

grou

p ex

plor

e th

e sc

ienc

e be

hind

the

term

"ro

cket

mot

ion.

" In

fac

t, th

ey m

ay b

e su

rpri

sed

tole

arn

that

roc

ketr

y go

t its

sta

rt w

ith th

e pu

blis

hing

of

abo

ok in

168

7 by

an

Eng

lish

scie

ntis

t nam

ed S

ir I

saac

New

ton.

In

his

wor

k, N

ewto

n st

ated

that

thre

e im

port

ant

scie

ntif

ic p

rinc

iple

s go

vern

the

mot

ion

of a

ll ob

ject

s.w

heth

er o

n ea

rth

or in

spa

ce. O

ver

time,

thes

e pr

inci

ples

have

bec

ome

know

n as

New

ton'

s la

ws

of m

otio

n.

Let's

Exp

lore

The

fol

low

ing

colle

ctio

n of

exp

erim

ents

hav

e be

en d

e-si

gned

to f

amili

ariz

e yo

ur g

roup

with

eac

h of

New

ton'

sth

ree

law

s. T

he a

ctiv

ities

may

be

pres

ente

d as

stu

dent

assi

sted

dem

onst

ratio

ns, o

r in

the

form

of

smal

l gro

upex

erci

ses.

Whe

neve

r po

ssib

le, e

ncou

rage

gro

up m

embe

rsto

col

lect

. ana

lyze

and

com

pare

dat

a. A

lso,

util

ize

the

1213

Exp

erim

ent

Tes

ting

Gra

vity

Mat

eria

ls: p

opco

rn

Dis

trib

ute

popc

orn

toth

e gr

oup.

Hav

e th

e gr

oup

plac

e se

vera

l pie

ces

in th

eir

hand

. Exp

lain

that

as

the

popc

orn

rest

s in

thei

r ha

nd it

is b

eing

act

ed u

pon

by f

orce

s. T

he f

orce

of

grav

ity is

try-

ing

to p

ull t

he p

opco

rn d

ownw

ard,

whi

le a

t the

sam

etim

e yo

ur h

and

is p

ushi

ng a

gain

st th

e po

pcor

n tr

ying

toho

ld it

up.

Now

try

unba

lanc

ing

the

forc

es b

y le

tting

the

popc

orn

fall

from

you

r ha

nd in

to y

our

mou

th. O

nce

done

, hav

e th

e gr

oup

desc

ribe

wha

t the

y di

d to

hav

e th

epo

pcor

n fa

ll fr

om th

eir

hand

. You

may

eve

n w

ish

to h

ave

the

grou

p m

embe

rs w

rite

dow

n th

e st

eps

they

use

d to

unba

lanc

e th

e fo

rces

act

ing

on th

e po

pcor

n.

Exp

lana

tion:

Hel

p th

e gr

oup

see

that

by

unba

lanc

-in

g fo

rces

, the

pop

corn

was

tran

sfor

med

fro

m a

sta

te o

fre

st to

a s

tate

of

mot

ion.

Gui

ding

Que

stio

nsW

hat f

orce

ret

urne

d th

e po

pcor

n ag

ain

to a

stat

e of

res

t? (

the

wal

l of

your

sto

mac

h)H

ow w

as th

e m

otio

nles

s po

pcor

n lik

e a

rock

eton

a la

unch

pad

? (b

oth

requ

ire

an u

nbal

anc-

ing

of f

orce

s to

mak

e th

em m

ove)

Wha

t for

ce k

eeps

a r

ocke

t mot

ionl

ess

on a

laun

ch p

ad?

(the

for

ce o

f th

e la

unch

pad

act

-in

g ag

ains

t the

for

ce o

f gr

avity

)C

ould

you

rep

eat t

he e

xper

imen

t in

the

wei

ghtle

ssne

ss o

f sp

ace?

(ye

s)W

hat w

ould

you

do

diff

eren

tly?

(pus

h th

e po

p-co

rn to

war

ds y

our

mou

th)

Exp

erim

ent -

Let

's G

et L

iftin

g

Mat

eria

ls: 1

6oz

soft

dri

nk b

ottle

stri

ngru

bber

ban

dw

ater

Div

ide

the

grou

p in

to te

ams.

Hav

e ea

ch te

am ta

ke a

nem

pty

16oz

sof

t dri

nk b

ottle

and

tie

a st

ring

aro

und

itsne

ck. N

ext,

take

a r

ubbe

r ba

nd a

nd c

ut it

so

that

it c

anbe

atta

ched

to th

e op

posi

te e

nd o

f th

e st

ring

. Now

, in-

stru

ct th

e te

ams

to p

ull t

he r

ubbe

r ba

nd a

nd m

easu

reho

w m

uch

it st

retc

hes

befo

re th

e em

pty

bottl

e lif

ts. N

ext,

have

eac

h te

am ta

ke th

e sa

me

bottl

e an

d til

l it w

ith w

a-te

r. A

gain

, pul

l on

the

rubb

er b

and

and

mea

sure

how

muc

h it

stre

tche

s be

fore

the

bottl

e lif

ts.

Exp

lana

tion:

As

the

team

s ob

serv

ed, a

cert

ain

amou

nt o

f un

-ba

lanc

ed f

orce

was

need

ed to

lift

the

bottl

e. H

owev

er, t

hegr

eate

r th

e m

ass

ofth

e ob

ject

, the

gre

ater

the

unba

lanc

ed f

orce

need

ed to

lift

it. O

bvi-

ousl

y, th

e id

ea o

fm

ass

is a

n im

port

ant

fact

or to

con

side

rw

hen

calc

ulat

ing

the

unba

lanc

ed f

orce

nec

-es

sary

to li

ft o

r m

ove

the

mas

s of

an

obje

ctlik

e a

rock

et.

Wou

ld th

e ex

peri

men

t wor

k th

e sa

me

in th

ew

eigh

tless

ness

of

spac

e? (

No,

the

abse

nce

ofgr

avity

wou

ld r

educ

e th

e fo

rce

nece

ssar

y to

mov

e th

e bo

ttle.

)O

n ea

rth,

wou

ld th

e sa

me

amou

nt o

f fo

rce

bene

eded

to p

ull t

he b

ottle

acr

oss

a de

sk?

(the

forc

e sh

ould

be

less

sin

ce y

ou a

re a

ctin

gag

ains

t fri

ctio

n ra

ther

than

gra

vity

.)

Wor

d to

Kno

w M

ass:

the

amou

nt o

f m

atte

rin

an

obje

ct

The

acc

eler

atio

n of

an

obje

ctis

dir

ectly

rel

ated

to th

e fo

rce

exer

ted

on th

at o

bjec

t and

oppo

site

ly r

elat

ed to

the

mas

sof

that

obj

ect.

acco

mpl

ishe

d by

igni

ting

engi

nes

in s

tage

s. T

his

allo

ws

for

spen

t eng

ines

to b

e se

para

ted

away

fro

m th

e m

ain

rock

et, t

here

by d

ecre

asin

g th

e ro

cket

's m

ass

whi

le in

-cr

easi

ng it

s ac

cele

ratio

n.

Exp

erim

ent G

ettin

g th

e Ju

mp

onG

ravi

tyB

reak

the

grou

p in

to te

ams

of tw

o fo

r th

is e

xper

i-m

ent.

Exp

lain

to th

e gr

oup

that

they

are

abo

ut to

expe

rien

ce N

ewto

n's

firs

t tw

o la

ws.

Fir

st, h

ave

the

team

spr

eten

d th

at th

ey a

re a

roc

ket o

n a

laun

ch p

ad. A

s th

eyst

and

with

thei

r ar

ms

at th

eir

side

, hav

e th

em ta

lkab

out t

he b

alan

ce o

f fo

rces

that

hol

d th

em s

tead

y. A

fter

a fe

w m

omen

ts, s

ugge

st th

at th

e te

ams

prep

are

them

-se

lves

for

lift

off.

Thi

s is

acc

ompl

ishe

d by

hav

ing

team

mem

bers

cro

uch

dow

n w

ith th

eir

hand

s to

uchi

ng th

efl

oor.

At t

he c

ount

of

thre

e, h

ave

each

team

mem

ber

jum

p in

to th

e ai

r.

Star

t by

poin

ting

out t

he u

sefu

lnes

s of

this

law

whe

nde

sign

ing

effi

cien

t roc

kets

. To

enab

le r

ocke

ts to

acc

eler

-at

e to

hig

her

elev

atio

ns w

ith g

reat

er p

aylo

ads,

des

igne

rsm

ust m

inim

ize

the

rock

et's

mas

s w

hile

max

imiz

ing

the

amou

nt o

f fo

rce

exer

ted

from

its

engi

nes.

Thi

s is

typi

cally

Aft

er th

e ju

mp,

dis

cuss

wha

t for

ces

beca

me

unba

l-an

ced

to c

ause

them

to m

ove

skyw

ard.

Als

o di

scus

sw

hat f

orce

s ca

used

them

to r

etur

n to

ear

th. U

se th

isdi

scus

sion

to le

ad th

em to

the

appl

icat

ion

of N

ewto

n's

seco

nd la

w. P

oint

out

that

in o

rder

to in

crea

se a

ccel

era-

tion,

they

eith

er h

ave

to d

ecre

ase

mas

s or

incr

ease

thru

St. S

ugge

st th

at te

am m

embe

rs s

tand

bac

k to

bac

kw

ith th

eir

arm

s lo

cked

and

rep

eat t

he e

xper

imen

t as

be-

fore

. "Su

rly

the

doub

ling

of le

g po

wer

will

impr

ove

acce

lera

tion!

" H

owev

er, a

s th

e te

ams

will

qui

ckly

dis

-co

ver,

the

doub

ling

of th

eir

thru

st w

as n

egat

ed b

y th

edo

ublin

g of

thei

r m

ass.

See

if th

e te

ams

can

figu

re o

ut h

ow to

incr

ease

thei

rth

rust

with

out i

ncre

asin

g th

eir

mas

s. F

or e

xam

ple.

hav

eon

e te

am m

embe

r ju

mp

into

the

air

whi

le b

eing

lift

edfr

om th

e w

aist

by

one

or tw

o ot

hers

.

S

Gui

ding

Que

stio

nsA

re th

ere

chal

leng

es w

hen

desi

gnin

g la

rger

rock

et e

ngin

es to

pro

duce

gre

ater

thru

st?

(yes

)H

ow d

id it

fee

l to

be li

fted

sky

war

d by

sev

eral

peop

le?

(som

ewha

t wei

ghtle

ss)

Was

the

job

of li

ftin

g ea

sier

as

mor

e pe

ople

join

ed in

? (y

es)

Exp

erim

ent -

Bou

ncin

g T

hing

sM

ater

ials

: Bas

ketb

all

Ten

nis

ball

Ask

a g

roup

mem

ber

tohe

lp y

ou b

y bo

unci

ng a

bas

-ke

tbal

l. A

t the

sam

e tim

e,be

gin

boun

cing

a te

nnis

bal

l.T

alk

abou

t the

dif

fere

nce

inm

ass

betw

een

the

tenn

is b

all

and

the

bask

et b

all.

Als

o m

entio

n th

at th

e te

nnis

bal

l cou

ld b

e th

row

nfa

ster

than

the

bask

etba

ll us

ing

the

sam

e am

ount

of

thru

st. L

astly

, com

pare

the

diff

eren

ce in

for

ce it

take

sto

bou

nce

them

equ

al h

eigh

ts.

Dig

ging

Dee

per

Ext

end

the

expe

rim

ent b

y pl

acin

g th

e te

nnis

bal

l on

top

of th

e ba

sket

ball

and

drop

ping

them

fro

m a

hei

ght o

fab

out 5

fee

t. If

don

e pr

oper

ly, t

he te

nnis

bal

l sho

uld

"sho

ot u

p" in

to th

e ai

r w

hile

the

bask

etba

ll ba

rely

leav

esth

e gr

ound

. In

fact

, the

hei

ght w

ill b

e so

gre

at th

at it

will

be im

poss

ible

to m

atch

with

a s

ingl

e bo

unce

of

the

ten-

nis

ball.

Try

mod

ifyi

ng th

e ex

peri

men

t by

appl

ying

grea

ter

forc

e as

you

dro

p th

e ba

lls.

Exp

lana

tion:

Far

mor

e en

ergy

is r

equi

red

to m

ake

the

bask

etba

ll bo

unce

the

sam

e di

stan

ce a

s th

e te

nnis

ball.

Thi

s is

bec

ause

the

bask

etba

ll ha

s m

ore

mas

s.(N

ewto

n's

seco

nd la

w)

Whe

n th

e te

nnis

bal

l is

plac

ed o

nth

e ba

sket

ball,

a tr

ansf

er o

f en

ergy

fro

m th

e ba

sket

ball

to th

e te

nnis

bal

l tak

es p

lace

. Thi

s is

the

sam

e pr

inci

ple

that

's u

sed

in th

e st

agin

g of

roc

kets

. Whe

n se

para

ted,

muc

h of

the

ener

gy in

the

mas

sive

low

er s

tage

s is

tran

s-_

ferr

ed to

the

light

er u

pper

sta

ges

resu

lting

in g

reat

erac

cele

ratio

n.01

Se

Exp

lana

tion:

By

now

, you

rea

lize

that

it ta

kes

far

mor

e fo

rce

to b

ounc

e a

bask

etba

ll th

an a

tenn

is b

all.

Of

cour

se, t

he b

aske

tbal

l is

heav

ier

than

a te

nnis

bal

l,bu

tit

is n

ot th

e w

eigh

t tha

t mak

es it

har

der

to b

ounc

e. I

fth

ere

wer

e no

gra

vity

, so

that

bot

h w

ere

wei

ghtle

ss, t

heba

sket

ball

wou

ld s

till b

e ha

rder

to b

ounc

e. T

his

is b

e-ca

use

the

bask

etba

ll ha

s a

grea

ter

amou

nt o

fmat

eria

lin

it (

mas

s). T

here

for,

acc

ordi

ng to

New

ton'

s Se

cond

law

, the

gre

ater

an

obje

ct's

mas

s, th

e gr

eate

r its

res

is-

tanc

e to

acc

eler

atio

n.

Gui

ding

Que

stio

nsW

hy is

it e

asie

r to

thro

w a

tenn

is b

all t

han

aba

sket

ball?

(le

ss m

ass)

Wha

t wou

ld b

e ea

sier

to s

low

dow

n, a

tenn

isba

ll or

a b

aske

tbal

l? (

a te

nnis

bal

l)O

n a

sing

le b

ounc

e, c

an y

ou m

atch

the

dis-

tanc

e th

e te

nnis

bal

l tra

vele

d w

hen

it w

as o

nth

e ba

sket

ball?

(no

t lik

ely)

Did

You

Kno

w -

the

larg

er th

e m

ass

of a

n ob

ject

in m

otio

n th

e gr

eate

r th

eun

bala

nced

for

ce n

eede

d to

sto

p it.

Tha

t's w

hy it

s so

dif

ficu

lt to

sto

p a

frei

ght t

rain

onc

e it

gets

mov

ing.

Its

mov

ing

mas

s po

sses

ses

a tr

emen

dous

amou

nt o

f in

ertia

.

19

to K

now

Ine

rtia

: A r

esis

tanc

e to

a c

hang

e in

mot

ion.

The

gre

ater

the

mas

s of

a m

ovin

g ob

ject

.th

e gr

eate

r its

iner

tia.

Did

You

Kno

w?

If th

e fo

rce

tobo

unce

a te

nnis

bal

l and

a b

aske

tbal

l10

fee

t int

o th

e ai

r di

ffer

s, w

hy th

enw

ill th

ey r

etur

n to

ear

th a

t the

sam

etim

e?In

159

0, a

man

by

the

nam

e of

Gal

ileo

(Gal

-uh-

LE

E-o

h)G

alile

i, fr

om P

isa

Ital

y, d

isco

vere

dth

at g

ravi

ty p

ulls

all

obje

cts

to e

arth

with

the

sam

e ac

cele

ratio

n (3

2ft/s

econ

d) r

egar

dles

S of

thei

r m

ass.

It i

s sa

id th

at h

e si

mul

tane

ousl

y dr

oppe

d a

10 p

ound

wei

ght a

nd a

1 p

ound

wei

ght f

rom

the

top

ofth

e L

eani

ng T

ower

of

Pisa

. A c

row

d of

stu

dent

s an

d pr

o-fe

ssor

s lo

oked

on

as b

oth

wei

ghts

hit

the

grou

nd a

t the

sam

e tim

e. G

alile

o ex

plai

ned

that

wha

t he

did

was

.. .

"no

diff

eren

t tha

n dr

oppi

ng te

n1

poun

d w

eigh

ts a

t the

sam

e tim

e as

the

1 po

und

wei

ght."

20

New

ton'

s T

hird

Law

For

ever

y ac

tion

ther

e is

alw

ays

anop

posi

te a

nd e

qual

rea

ctio

n.

Exp

lain

to th

e gr

oup

that

with

roc

kets

, the

act

ion

isth

e ex

pelli

ng o

f ga

s ou

t of

the

engi

ne. T

he r

eact

ion

is th

em

ovem

ent o

f th

e ro

cket

in th

e op

posi

te d

irec

tion.

Of

cour

se y

ou m

ight

bel

ieve

that

a r

ocke

t mov

es b

y pu

sh-

ing

off

agai

nst t

he s

urro

undi

ng a

ir. H

owev

er, i

f th

is w

ere

the

case

, spa

ce tr

avel

wou

ld b

e im

poss

ible

due

to th

eab

senc

e of

air

in s

pace

.

21

Exp

erim

ent

Kic

king

Into

Act

ion

The

bes

t way

for

the

grou

p to

und

erst

and

the

prin

-ci

ple

of "

actio

n-re

actio

n" is

to e

xper

ienc

e it

them

selv

es.

Beg

in b

y fi

ndin

g a

smoo

th s

urfa

ce o

n w

hich

to s

tret

chou

t. W

hile

lyin

g on

thei

r ba

cks

with

thei

r ar

ms

at th

eir

side

, hav

e th

em k

ick

thei

r fe

et f

orw

ard.

If

the

surf

ace

issm

ooth

eno

ugh,

they

sho

uld

begi

n m

ovin

g in

the

oppo

-si

te d

irec

tion

of th

eir

kick

s.

Que

stio

ns to

Ans

wer

How

is w

ater

spr

ayin

g fr

om a

gar

den

hose

sim

ilar

to th

is e

xper

imen

t? (

forc

e of

wat

erfr

om th

e no

zzle

tend

s to

pus

h ho

se in

opp

o-si

te d

irec

tion)

How

is y

our

kick

ing

like

the

thru

st f

rom

aro

cket

's e

ngin

e? (

the

engi

ne's

thru

st m

oves

the

rock

et f

orw

ard)

Wha

t hap

pens

if y

ou h

eld

a st

ack

of b

ooks

on

your

sto

mac

h? (

It w

ould

it ta

ke m

ore

ener

gyto

mov

e th

e sa

me

dist

ance

as

befo

re)

How

is a

ddin

g w

eigh

t an

exam

ple

of N

ewto

n's

seco

nd la

w o

f m

otio

n? (

incr

easi

ng th

e m

ass

decr

ease

s th

e ac

cele

ratio

n)

Exp

erim

ent C

omin

g an

d G

oing

Mat

eria

ls: N

ylon

str

ing

Dri

nkin

g st

raw

2 ch

airs

tape

long

bal

loon

Hav

e a

coup

le o

f gr

oup

mem

bers

hel

p yo

u w

ith th

ene

xt e

xper

imen

t.U

sing

an

8' p

iece

of

nylo

n st

ring

, thr

ead

it th

roug

h a

1" p

iece

of

drin

king

str

aw. S

uspe

nd th

e si

ring

bet

wee

ntw

o ch

airs

or

a w

ide

door

way

as

show

n. N

ext,

inna

te a

long

bal

loon

and

atta

ch it

to th

e 1"

str

aw w

ith a

pie

ce o

fta

pe. S

tart

ing

at o

ne e

nd o

f th

e st

ring

, rel

ease

the

bal-

loon

and

obs

erve

how

it tr

avel

s al

ong

the

stri

ng.

Exp

lana

tion

- H

elp

the

grou

p se

e th

at th

e ac

tion

ofth

e ai

r le

avin

g th

e ba

lloon

in o

ne d

irec

tion

prov

ides

the

mov

emen

t of

the

ballo

on in

the

oppo

site

dir

ectio

n.

Gui

ding

Que

stio

nsW

ould

the

size

or

shap

e of

the

ballo

on e

ffec

tits

per

form

ance

? (y

es)

Wou

ld a

ddin

g w

eigh

t to

the

ballo

on e

ffec

t its

perf

orm

ance

? (y

es)

23

Lee

s su

mm

ariz

eT

ake

this

tim

e to

sum

mar

ize

wha

t the

gro

up h

asle

arne

d so

far

. Rem

ind

then

, tha

t for

a r

ocke

t to

lift o

fffr

om a

laun

ch p

ad, f

orce

mus

t be

exer

ted

(fir

st la

w)

to u

n-ba

lanc

e th

e pr

esen

t for

ces

at w

ork.

The

rat

e at

whi

ch th

ero

cket

leav

es th

e la

unch

pad

(se

cond

law

) w

ill b

e de

ter-

min

ed b

y th

e m

ass

of th

e ro

cket

and

its

fuel

, alo

ng w

ithth

e fo

rce

that

is p

rodu

ced

whe

n th

e fu

el is

bur

ned.

The

reac

tion.

or

mot

ion,

of

the

rock

et a

way

fro

m th

e la

unch

pad

(thi

rd la

w)

is e

qual

to a

nd o

ppos

ite f

rom

the

actio

n or

thru

st. o

f th

e en

gine

.

Goi

ng B

eyon

d: B

uild

you

ow

n H

ero

Eng

ine

Exp

lain

toth

e gr

oup

that

aro

und

700B

C, a

Gre

ekm

an b

y th

e na

me

of H

eron

of

Ale

xand

ria

inve

nted

aro

cket

like

dev

ice

late

r to

be

know

n(

as a

"H

ero

Eng

ine.

" H

eron

r5,5

)m

ount

ed a

sph

ere

on to

p of

a w

a-te

r ke

ttle.

A f

ire

mou

nted

bel

owth

e ke

ttle

turn

ed th

e w

ater

into

stea

m, a

nd th

e ga

s tr

avel

edth

roug

h pi

pes

to th

e sp

here

. Tw

oL

-sha

ped

tube

s on

opp

osite

sid

esof

sph

ere

allo

wed

the

gas

to e

s-ca

pe, a

nd in

doi

ng s

o ga

ve a

thru

stto

the

sphe

re c

ausi

ng it

to r

otat

e.L

ittle

did

Her

on k

now

that

his

engi

ne w

as a

n ex

celle

nt e

xam

ple

ofN

ewto

n's

thre

e la

ws

of m

otio

n. A

lso,

littl

e di

d he

kno

w th

athi

s in

vent

ion

wou

ld g

ive

birt

h to

the

law

n sp

rink

ler.

Use

the

follo

win

gin

stru

ctio

ns to

cre

ate

1. L

ay a

n al

umin

um c

an o

n its

side

. Usi

ng a

nai

l, ca

refu

lly p

unch

four

equ

ally

spa

ced

hole

s ju

stab

ove

and

arou

nd th

e bo

ttom

rim

. Bef

ore

rem

ovin

g th

e na

il,pu

sh it

slig

htly

to th

e ri

ght s

oth

at th

e ho

le is

in a

sla

nted

dir

ectio

n.2.

Ben

d th

e ca

n's

open

er le

ver

stra

ight

up

and

tie a

shor

t len

gth

of n

ylon

str

ing

to it

.3.

Im

mer

se th

e ca

n in

wat

er u

ntil

it is

fill

ed. A

s th

e ca

nis

lift

ed b

y its

str

ing,

wat

ch h

ow w

ater

leav

ing

the

can

thro

ugh

the

hole

s st

arts

it s

pinn

ing.

Exp

lana

tion:

1st

Law

The

can

spi

ns b

ecau

se g

ravi

typu

lling

wat

er th

roug

h th

e ho

les

crea

tes

an im

bala

nce

offo

rces

on

the

can.

2nd

Law

The

rat

e of

acce

lera

tion

will

vary

with

the

mas

sof

the

can

and

the

wat

er in

it. I

t will

also

var

y w

ith th

efo

rce

at w

hich

the

wat

er le

aves

the

hole

s. T

his

forc

e is

dep

ende

nt u

pon

on th

e nu

mbe

r an

dsi

ze o

f ho

les

used

, alo

ng w

ith th

e vo

lum

e of

wat

er a

bove

the

hole

s. 3

rd L

aw T

he c

an r

otat

es o

ppos

ite f

rom

the

di-

rect

ion

of th

e w

ater

leav

ing

the

can.

your

ow

n H

ero

type

engi

ne. T

ime

perm

it-tin

g, u

se th

is a

s a

team

s

activ

ity o

r a

grou

p de

mon

-."

1,1I

;),:)

',.

stra

tion.

Eith

er w

ay, t

his

1'

,

1'ac

tivity

doe

s a

nice

job

of ty

ing

in N

ewto

n's

thre

e la

ws.

Gui

ding

Que

stio

ns:

If y

ou a

dded

wei

ght t

o th

e ca

n w

ould

it ta

ke a

long

er o

r sh

orte

r pe

riod

of

time

for

the

can

tost

art s

pinn

ing?

(lo

nger

)O

nce

the

wei

ghte

d ca

n st

arte

d to

spi

n, w

ould

itta

ke a

long

er o

r sh

orte

r pe

riod

of

time

for

it to

stop

? (l

onge

r)

S

II. b

uild

ing

On

The

bas

ics

Roc

ket R

un-c

low

nR

ocke

ts d

o no

t rel

y on

the

dyna

mic

s of

flig

ht f

ortr

avel

.R

ocke

t eng

ines

use

noz

zles

to in

crea

se a

nd d

irec

tth

rust

.R

ocke

ts a

re lo

ng a

nd b

alan

ced

for

reas

ons

of e

ffi-

cien

cy a

nd s

tabi

lity.

In th

e at

mos

pher

e, f

ins

are

used

to b

alan

ce, c

on-

trol

and

sta

biliz

e ro

cket

s.R

ocke

ts a

re s

trea

mlin

ed to

max

imiz

e pe

rfor

man

cew

ithin

the

atm

osph

ere.

Bac

kgro

und

Ove

r a

long

and

exc

iting

his

tory

, roc

kets

hav

e ev

olve

din

to m

ight

y ve

hicl

es c

apab

le o

f la

unch

ing

spac

ecra

ft b

e-yo

nd th

e re

ache

s of

our

pla

net.

Roc

kets

hav

e br

ough

t us

man

y w

onde

rs. T

hey

have

car

ried

ast

rona

uts

to th

e m

oon,

give

n us

imag

es f

rom

the

edge

s of

the

sola

r sy

stem

, and

plac

ed s

atel

lites

into

orb

it pr

ovid

ing

inst

anta

neou

s gl

obal

com

mun

icat

ions

. Few

exp

erie

nces

can

com

pare

with

the

exci

tem

ent a

nd th

rill

of w

atch

ing

a ro

cket

pow

ered

veh

icle

like

the

Spac

e Sh

uttle

thun

der

into

spa

ce. Y

et, w

ith a

ll of

thes

e de

velo

pmen

ts ta

king

pla

ce a

roun

d us

, peo

ple

still

fail

to c

ompr

ehen

d th

e ba

sic

prin

cipl

es o

f ro

cket

ry. F

or e

x-am

ple,

the

follo

win

g ar

e si

x of

the

mos

t com

mon

ly a

sked

ques

tions

of

NA

SA s

cien

tists

.C

omm

only

Ask

ed Q

uest

ions

Q. D

o ro

cket

s re

ally

fly

?Q

. Why

do

rock

et e

ngin

es h

ave

nozz

les?

Q. W

hy a

re r

ocke

ts s

o lo

ng?

Q. I

f ro

cket

s do

n't f

ly, w

hy d

o th

ey h

ave

fins

?Q

. Why

are

roc

kets

so

stre

amlin

ed?

Q. W

hy m

ust r

ocke

ts b

e ba

lanc

ed?

Use

this

less

on to

hel

p yo

ur g

roup

exp

lore

the

an-

swer

s to

thes

e qu

estio

ns w

hile

pre

pari

ng th

em f

orad

ditio

nal l

earn

ing.

The

ans

wer

s to

the

ques

tions

may

be e

xplo

red

thro

ugh

the

use

of s

tude

nt a

ssis

ted

dem

on-

stra

tions

or

actu

al h

ands

-on

invo

lvem

ent.

Dis

cuss

ion

Intr

oduc

e th

e si

x qu

estio

ns to

your

gro

up. E

xpla

in th

at th

ey w

illbe

exp

lori

ng th

e an

swer

s to

thes

equ

estio

ns th

roug

h a

seri

es o

f ha

nds-

on e

xper

imen

ts. B

e su

re to

em

phas

ize

that

the

goal

of

this

less

on is

to s

earc

h fo

ran

swer

s ra

ther

than

mem

oriz

e so

lutio

ns.

Q: D

o R

ocke

ts R

eally

Fly

?A

: Air

is a

ll ar

ound

us.

Our

pla

net i

s su

rrou

nded

by

a la

yer

of a

ir c

alle

d th

e at

mos

pher

e he

ld in

pla

ce b

ygr

avity

. Alth

ough

air

can

't be

see

n, it

has

sub

stan

ce. I

nfa

ct, a

ir h

as s

o m

uch*

subs

tanc

e th

at it

can

hol

d up

air

-cr

aft t

he s

ize

of a

sch

ool b

us th

roug

h a

forc

e kn

own

aslif

t. O

n an

air

plan

e, li

ft is

pro

duce

d as

the

plan

e bu

ilds

up s

peed

for

take

off.

As

the

plan

e ra

ces

dow

n th

e ru

n-.

way

, the

und

ersi

de o

f its

win

gs b

egin

to r

est u

pon

anev

er in

crea

sing

for

ce o

f ai

r ru

shin

g be

neat

h th

em. W

hen

the

pres

sure

of

air

unde

r th

e w

ings

is g

reat

eno

ugh

to s

uppo

rt th

ew

eigh

t of

the

plan

e, li

ft o

ccur

s. T

his

is s

ame

forc

e pe

ople

fee

l whe

n th

eyst

ick

thei

r ha

nd o

ut th

e w

indo

w o

f a

fast

mov

ing

car.

The

for

ce o

f th

eai

r hi

tting

the

palm

of

thei

rha

nd c

an a

ctua

lly p

rovi

deen

ough

pre

ssur

e to

sup

-po

rt it

in m

id a

ir.

2627

Exp

erim

ent -

Try

a L

ittle

Lift

Mat

eria

ls: S

trip

s of

pap

er 2

"x8"

Hel

p yo

ur g

roup

see

that

an

air

stre

am h

as li

ftin

gpo

wer

by

blow

ing

on a

pie

ce o

f pa

per.

Cut

a s

trip

of

pa-

per

2 in

ches

by

8 in

ches

. Hol

ding

one

end

aga

inst

thei

rch

in, h

ave

them

blo

w o

n th

e st

rip.

As

they

blo

w, a

n ai

rst

ream

for

ms

and

the

stri

p fl

ies

up. B

low

har

der,

and

itfl

ies

high

er. S

top

blow

ing

and

it st

ops

flyi

ng.

Gui

ding

Que

stio

nsW

hat w

ould

hap

pen

if y

ou in

crea

sed

the

size

of th

e pa

per?

(fo

rce

ofai

r w

ould

nee

d to

incr

ease

)W

hy is

lift

less

of

afa

ctor

for

mov

esro

cket

s.(R

ocke

tsdo

n't r

ely

on a

cus

h-io

n of

air

for

flig

ht)

Air

Pig

ging

Pee

per

Alth

ough

air

is e

ssen

tial f

or th

e fl

ight

of

airp

lane

san

d je

ts. t

he r

ever

se c

an b

e sa

id a

bout

win

gles

s ro

cket

s.A

s yo

u re

call

from

the

disc

ussi

on o

f N

ewto

n's

thir

d la

w.

the

forc

e of

gas

leav

ing

a ro

cket

's e

ngin

e pr

ovid

es a

neq

ual a

nd o

ppos

ite f

orce

whi

ch li

fts

the

rock

et s

kyw

ard.

Com

pare

d to

air

plan

es a

nd je

ts w

hich

rel

y up

on th

e at

-m

osph

ere

to li

ft a

nd p

ull t

hem

selv

es a

long

, roc

kets

mov

ew

ithou

t. th

e ne

ed o

f at

mos

pher

e. T

his

is e

spec

ially

ess

en-

tial f

or tr

avel

ing

the

wei

ghtle

ssne

ss o

f sp

ace

whe

reat

mos

pher

e is

non

exis

tent

.

Bal

loon

mov

es

4111

(-

28

Exp

erim

ent -

Act

ion/

Rea

ctio

n

Mat

eria

ls: 5

" ba

lloon

s

Tak

e a

5 in

ch b

allo

on a

nd in

flat

e it

to c

apac

ity. N

ow,

rele

ase

the

ballo

on a

nd w

atch

its

mov

emen

ts. A

s th

egr

oup

will

not

e, th

e ai

r ru

shin

g fr

om th

e ba

lloon

's o

pen

end

prov

ides

an

equa

l and

opp

osite

rea

c-tio

n of

for

war

d m

otio

n. (

New

ton'

s 3r

dL

aw)

Gui

ding

Que

stio

nsW

hat w

ould

hap

pen

if y

ouin

crea

sed

the

size

of

the

ballo

on?

(sho

uld

see

sim

i-la

r re

sults

)W

hat w

ould

hap

pen

if y

ouad

ded

wei

ght t

o th

e ba

l-lo

on?

(acc

eler

atio

nw

ould

dec

reas

eN

ewto

n's

2nd

law

)

Q: W

hy D

o R

ocke

t Eng

ines

Hav

e N

ozzl

es?

A: T

he p

urpo

se o

f th

e no

zzle

isto

incr

ease

the

acce

lera

tion

of th

ega

ses

as th

ey le

ave

the

rock

et,

ther

eby

max

imiz

ing

the

thru

st. I

tdo

es th

is b

y cu

tting

dow

n th

eop

enin

g th

roug

h w

hich

the

gase

sca

n es

cape

. The

noz

zle

in a

sol

id-

prop

ella

nt e

ngin

e is

an

open

ing

atth

e ba

ck o

f th

e ro

cket

that

per

mits

the

hot e

xpan

ding

gas

es to

esc

ape.

The

nar

row

par

t of

the

nozz

le is

the

thro

at. J

ust b

eyon

d th

e th

roat

isth

e ex

it co

ne.

dbb

29

AW

AY

!

Exp

erim

ent A

dd a

Noz

zle

Mat

eria

ls: d

rink

ing

stra

ws

scis

sors

tape

5" b

allo

on

Usi

ng th

e 5

inch

bal

loon

fro

m th

e ea

rlie

r ex

peri

men

tin

sert

a 1

inch

pie

ce o

f pl

astic

dri

nkin

g st

raw

into

its

open

end

. Be

sure

the

"rol

led"

end

of

the

ballo

on is

clip

ped

off

so th

at th

e ba

lloon

can

be

tape

d se

cure

ly to

the

stra

w. I

nfla

te th

e ba

lloon

then

rel

ease

it w

ith th

est

raw

atta

ched

. Hav

e th

e gr

oup

note

the

chan

ge in

the

ballo

on's

mov

emen

t. R

athe

r th

an f

lyin

g w

ildly

, it n

owm

oves

in c

ircl

es. A

s th

e gr

oup

can

see,

the

stra

w in

-cr

ease

s an

d di

rect

s th

e fl

ow o

f ai

r fr

om th

e ba

lloon

.

Gui

ding

Que

stio

nsW

hat w

ould

hap

pen

if y

ou a

dded

leng

th to

the

nozz

le?

(Per

form

ance

wou

ld e

vent

ually

decr

ease

)W

hat w

ould

hap

pen

if y

ou d

ecre

ased

the

di-

amet

er o

f th

e no

zzle

? (P

erfo

rman

ce w

ould

even

tual

ly d

ecre

ase)

Pig

ging

Pee

per

Noz

zles

in e

very

day

use.

If p

ossi

ble,

hel

p th

e gr

oup

see

how

a n

ozzl

e w

orks

us-

ing

a ga

rden

hos

e. T

urn

on th

e w

ater

and

wat

ch h

ow it

flow

s fr

om th

e ho

se. N

ow p

ut o

n a

spra

y no

zzle

and

ob-

serv

e th

e ch

ange

in w

ater

leav

ing

the

hose

. Try

set

ting

the

nozz

le d

own

on a

sm

ooth

sur

face

whi

le th

e w

ater

isru

nnin

g. C

hanc

es a

re th

e ho

se w

ill b

egin

to m

ove.

Can

the

grou

p gu

ess

whi

ch o

f N

ewto

n's

thre

e la

ws

of m

otio

nar

e at

wor

k? (

3rd

law

, act

ion/

reac

tion)

30

Q: W

hy A

re R

ocke

ts S

o L

ong?

A: B

uild

ing

an e

ffic

ient

roc

ket e

ngin

e is

onl

y pa

rt o

fth

e pr

oble

m to

pro

duci

ng a

suc

cess

ful r

ocke

t. T

he r

ocke

tm

ust a

lso

be s

tabl

e in

flig

ht. M

akin

g a

rock

et. s

tabl

e re

-qu

ires

som

e fo

rm o

f co

ntro

l sys

tem

. The

sim

ples

t of

all

cont

rols

is a

stic

k. T

he C

hine

se f

ire-

arro

ws

wer

e si

mpl

ero

cket

s m

ount

ed o

n th

e en

ds o

f st

icks

.

:OW

Exp

erim

ent -

Add

a S

tick

Mat

eria

ls: s

traw

sta

pe5"

bal

loon

Tak

e a

plas

tic d

rink

ing

stra

w a

nd in

sert

its

end

into

anot

her

plas

tic s

traw

. Cut

one

of

the

stra

ws

so th

at th

eto

tal l

engt

h of

the

two

stra

ws

com

bine

d is

13

inch

es. U

s-in

g th

e ba

lloon

with

the

nozz

le a

ttach

ed f

rom

the

earl

ier

expe

rim

ent,

tape

the

13 in

ch s

traw

alo

ng th

ele

ngth

of

the

nozz

le. C

aref

ully

infl

ate

the

ballo

on th

en r

elea

se it

. Wat

ch h

ow th

eba

lloon

roc

ket m

oves

with

the

stra

ws

at-

tach

ed. H

ave

the

grou

p ob

serv

e th

ero

cket

's u

pwar

d m

ovem

ent a

long

with

its

slig

ht r

otat

ion.

Gui

ding

Que

stio

nsW

hat w

ould

hap

pen

if y

ou in

crea

sed

the

leng

th o

f th

e st

raw

. (th

e ad

ded

wei

ght w

ould

even

tual

ly d

ecre

ase

perf

orm

ance

)W

hy a

re th

e st

icks

on

bottl

e ro

cket

s so

long

?(T

o pr

ovid

e m

axim

um c

ontr

ol f

or s

afet

y)

31

Q: I

f R

ocke

ts D

on't

Fly,

.Why

Do

The

y H

ave

Fins

?A

: Roc

kets

are

sta

biliz

ed b

y th

e ef

fect

s of

air

mov

e-m

ent o

n th

eir

fins

whi

ch f

unct

ion

as c

ontr

ols.

Eve

n a

rock

et, l

ong

in s

tatu

re, w

ill r

oll,

pitc

h, a

nd y

aw if

the

forc

e of

air

hit-

ting

its s

urfa

ce is

not

con

trol

led.

Thi

nk o

f a

rock

et a

s a

wea

ther

van

e.T

he r

easo

n th

at th

e w

heth

erva

ne a

rrow

poi

nts

into

the

win

d is

that

the

tail

of th

ear

row

has

a m

uch

larg

ersu

rfac

e ar

ea th

an th

e ar

-ro

whe

ad. T

he f

low

ing

air

impa

rts

a gr

eate

rfo

rce

to th

e ta

ilth

an th

e he

ad, a

ndth

eref

ore

the

tail

ispu

shed

aw

ay.

For

a ro

cket

to f

ly p

rope

rly,

pitc

h an

d ya

w a

xes

are

the

mos

t im

port

ant:

to c

ontr

ol b

ecau

se a

ny m

ovem

ent.

inei

ther

of

thes

e tw

o di

rect

ions

will

cau

se th

e ro

cket

to g

oof

f co

urse

. The

rol

l axi

s do

es n

ot, a

ffec

t the

flig

ht p

ath.

In

fact

, a r

ollin

g m

otio

n w

ill h

elp

stab

ilize

the

rock

et th

esa

me

way

a p

rope

rly

pass

ed f

ootb

all i

s st

abili

zed

by r

oll-

ing

in f

light

. How

ever

this

rol

ling

mot

ion

does

tend

tous

e up

som

e of

the

ener

gy n

eede

d fo

r fo

rwar

d m

otio

n.

¢oti

try

Exp

erim

ent -

Add

a F

in

Mat

eria

ls: 3

" sq

uare

s of

pap

erta

pesc

isso

rs

Tak

e a

piec

e of

pap

er 3

inch

essq

uare

and

cut

it in

hal

f di

agon

ally

.(T

he la

rge

"Pos

t-It

s" w

ork

wel

lfo

r th

is e

x-pe

r-fu

lcra

.)

Usi

ng th

e ba

lloon

and

str

aws

from

the

earl

ier

activ

ity,

tape

the

piec

es o

f pa

per

to th

e bo

ttom

of

the

stra

w a

ssh

own.

Inf

late

the

ballo

on th

en r

elea

se it

. Hav

e gr

oup

mem

bers

not

e ho

w th

e fi

ns s

eem

to h

elp

stab

ilize

the

flig

ht o

f th

e ba

lloon

, esp

ecia

lly it

s ro

lling

mot

ion.

Gui

ding

que

stio

nsA

re th

ere

cert

ain

fin

conf

igur

atio

ns th

at w

ork

bette

r th

an o

ther

s? (

yes)

Wha

t wor

ks b

ette

r, tw

o or

fou

r fi

ns?

(tw

ose

em to

wor

k be

tter

due

to le

ss d

rag)

Wha

t hap

pens

if y

ou u

sed

two

ballo

ons

in-

stea

d of

one

? (g

reat

er th

rust

sho

uld

incr

ease

perf

orm

ance

- N

ewto

n's

seco

nd la

w.)

Q: W

hy a

re r

ocke

ts s

o St

ream

lined

?A

: Whe

n a

rock

et is

mov

ing,

fri

ctio

n fr

om th

e at

mo-

sphe

re s

low

s it

dow

n. A

ny p

art o

f th

e ro

cket

that

stic

ksou

t con

trib

utes

to th

e pr

oble

m. T

o re

duce

the

amou

nt o

ffr

ictio

n (o

r dr

ag)

on a

roc

ket,

it sh

ould

be

desi

gned

tosl

ice

clea

nly

thro

ugh

the

air.

A p

rope

rly

desi

gned

roc

ket

is s

aid

to b

e st

ream

lined

. Thi

s m

eans

that

air

pas

sing

arou

nd th

e ou

tsid

e of

an

obje

ct f

low

s in

sm

ooth

line

s.Po

orly

des

igne

d ro

cket

s, o

nes

that

pro

duce

dra

g, c

ause

the

air

to tu

mbl

e. T

he p

rope

r te

rm f

or tu

mbl

ing

air

istu

rbul

ence

.

Tra

iling

edge

15

32

AW

AY N

ose

Con

es

The

sha

pe o

f th

e no

se c

one

has

a gr

eat e

ffec

t on

the

amou

nt o

f dr

ag th

at a

roc

ket e

xper

ienc

es. A

par

abol

icno

se c

one

crea

tes

the

leas

e am

ount

of

drag

. A g

ood

leng

th to

wid

th r

atio

is th

ree

to o

ne.

100% 80 40 20 0

Fin

s A s

wep

t bac

k fi

n cr

eate

s le

ss d

rag

than

a s

trai

ght o

rfo

rwar

d-sw

ept f

in. A

lso

roun

ded

corn

ers

on a

fin

cre

ate

less

dra

g th

an s

harp

cor

ners

.

Exp

erim

ent -

test

ing

turb

ulen

ce

Mat

eria

ls: c

onst

ruct

ion

pape

rsc

isso

rs

Cut

a 2

inch

squ

are

from

a p

iece

of

cons

truc

tion

pa-

per.

Hol

d th

e sq

uare

abo

ut 2

inch

es in

fro

nt o

f a

burn

ing

cand

le a

nd a

bout

4 in

ches

fro

m y

ou a

s sh

own

in th

e ill

us-

trat

ion.

Blo

w h

ard

agai

nst t

he s

quar

e an

d ob

serv

e th

em

ovem

ent o

f th

e fl

ame.

If

the

grou

p se

es a

ny u

nusu

alm

ovem

ent i

n th

e fl

ame

they

are

obs

ervi

ng tu

rbul

ence

.N

ow, t

ake

a 2

inch

by

4 in

ch p

iece

of

cons

truc

tion

pape

ran

d fo

ld it

into

the

shap

e of

a w

ing

as s

how

n in

the

illus

-tr

atio

n. B

low

ing

as b

efor

e, o

bser

ve th

em

ovem

ent o

f th

e fl

ame.

As

the

grou

p w

ill n

ote,

smoo

th, r

ound

ed s

ur-

face

s pr

oduc

e le

ss4

turb

ulen

ce th

an f

lat

ones

. Of

cour

se, o

nce

in s

pace

, the

sha

pe o

fth

e ro

cket

mat

ters

little

. For

exa

mpl

e, o

urea

rth,

whi

ch tr

avel

sar

ound

the

sun

at a

spee

d of

66,

600

mph

,ha

s m

ore

in c

omm

onw

ith a

bow

ling

ball

==

>th

an a

roc

ket.

Gui

ding

Que

stio

nsD

oes

the

size

of

the

pape

r ge

nera

te m

ore

or le

sstu

rbul

ence

? (D

epen

ds o

n th

e sh

ape

of th

e le

ad-

ing

edge

)D

oes

the

smoo

thne

ss o

f th

e pa

per

gene

rate

mor

e or

less

turb

ulen

ce?

(May

tend

to p

rodu

cele

ss)

34

Q: W

hy m

ust r

ocke

ts b

e ba

lanc

ed?

A: T

here

is a

n im

agin

ary

poin

t in

any

rock

et w

here

ther

e is

exa

ctly

the

sam

e su

rfac

e ar

ea o

n on

e si

de o

f th

epo

int a

s on

the

othe

r. T

his

spot

is c

alle

d th

e C

ente

r of

Pres

sure

( ®

). T

here

is a

lso

a sp

ot in

any

roc

ket w

here

all o

f its

mas

s is

per

fect

ly b

alan

ced.

Thi

s sp

ot is

kno

wn

as it

s C

ente

r of

Gra

vity

( S

). I

n or

der

for

a ro

cket

to r

e-m

ain

stab

le w

hile

in th

e ai

r or

in th

e w

eigh

tless

ness

of

spac

e, th

e C

) an

d Si

sho

uld

be n

o cl

oser

than

one

-hal

fth

e di

stan

ce e

qual

to th

e la

rges

t dia

met

er o

f th

e bo

dy. I

fth

ey a

re in

the

sam

e pl

ace,

or

very

nea

r ea

ch o

ther

, the

rock

et w

ill tr

y to

rot

ate

abou

t its

cen

ter

of g

ravi

ty.

\ \U

nsta

ble

rock

et

Stab

le r

ocke

t

Exp

erim

ent b

room

Lau

nch

Mat

eria

ls: B

room

If y

ou tr

ied

to to

ss th

e he

ad o

f a

broo

m in

to th

e ai

r, it

wou

ld b

egin

to tu

mbl

e ar

ound

its

cent

er o

f gr

avity

.T

hat's

bec

ause

the

cent

er o

f gr

avity

of

a br

oom

hea

d an

dth

e ce

nter

of

pres

sure

use

d to

lift

it a

re to

o cl

ose

to-

geth

er. A

rul

e of

thum

b is

that

the

dist

ance

bet

wee

n th

etw

o po

ints

sho

uld

be n

o le

ss th

at 1

/2 th

e la

rges

t dia

m-

eter

of

the

body

.

Tes

t thi

s by

toss

ing

an e

ntir

e br

oom

into

the

air.

As

the

grou

p w

ill o

bser

ve, t

he b

room

han

dle

stab

ilize

s th

ebr

oom

hea

d by

shi

ftin

g th

e ce

nter

of

grav

ity a

way

fro

mth

e ce

nter

of

pres

sure

. You

can

toss

the

broo

m a

ll yo

uw

ant b

ut it

is d

iffi

cult

to s

pin

it en

d ov

er e

nd. N

ot b

adst

abili

ty if

it w

ere

a ro

cket

. In

fact

, it w

ould

take

an

in-

cred

ible

am

ount

of

"unn

atur

al"

late

ral p

ress

ure

agai

nst

its lo

wer

end

to th

row

this

type

of

rock

et o

ff c

ours

e.

Gui

ding

Que

stio

ns

Whe

re is

the

broo

m's

cen

ter

of g

ravi

ty?

(its

bala

ncin

g po

int)

Whe

re is

the

broo

ms

cent

er o

f pr

essu

re?

(the

poin

t at w

hich

a s

ilhou

ette

of

the

broo

m b

al-

ance

s)D

oes

the

leng

th o

f th

e br

oom

han

dle

mak

e a

diff

eren

ce in

the

broo

m's

sta

bilit

y? (

yes)

If th

e w

eigh

t of

the

broo

m h

ead

was

in-

crea

sed,

wou

ld it

bec

ome

mor

e or

less

sta

ble?

(mor

e st

able

)W

hat d

o yo

u co

mpr

o-m

ise

whe

n ad

ding

wei

ght

to th

e br

oom

hea

d? (

per-

form

ance

New

ton'

s 2n

dla

w)

Wha

t are

sim

ilari

ties

be-

twee

n th

e br

oom

and

an

arro

w?

(wei

ght a

t the

top

and

leng

th)

3637

17

S

III. L

et's

Get

Lau

nchi

ng

Roc

ket R

un-d

own

Roc

kets

nee

d to

be

prop

erly

wei

ghte

d fo

r m

axi-

mum

sta

bilit

y.R

ocke

ts n

eed

to b

e pr

oper

ly d

esig

ned

for

max

i-m

um p

erfo

rman

ce.

The

alti

tude

and

vel

ocity

of

mod

el r

ocke

ts c

anbe

det

erm

ined

mat

hem

atic

ally

.R

ocke

t fue

l nee

ds to

be

prop

erly

for

mul

ated

and

wei

ghte

d to

pro

vide

max

imum

thru

st.

back

grou

ndT

his

less

on is

des

igne

d to

hel

p th

e gr

oup

appl

y w

hat

they

lear

ned

in th

e pr

evio

us tw

o le

sson

s th

roug

h a

uniq

uest

ep-b

y-st

ep p

robl

em s

olvi

ng a

ppro

ach.

Thi

s in

clud

es th

ede

sign

, con

stru

ctio

n, a

nd la

unch

ing

of 2

-lite

r bo

ttle

rock

-et

s. B

e su

re to

pho

toco

py th

e ap

prop

riat

e pa

ges

from

this

less

on a

nd d

istr

ibut

e th

em to

gro

up m

embe

rs. T

ime

per-

mitt

ing,

gro

up m

embe

rs s

houl

d be

allo

wed

to w

ork

at th

eir

own

pace

in te

ams

of 2

-3. Y

ou m

ay n

eed

to h

ave

addi

tiona

lla

unch

ers

on h

and

to c

ut d

own

on th

e am

ount

of

wai

ttim

e. E

vent

ually

, a f

rien

dly

com

petit

ion

will

occ

ur b

etw

een

the

grou

ps to

det

erm

ine

who

bui

lt th

e be

st r

ocke

t. W

hen

this

hap

pens

, use

this

as

an o

ppor

tuni

ty li

t- c

oope

rativ

ele

arni

ng to

take

pla

ce.

For

lear

ners

with

acc

ess

to a

n IB

M c

ompa

tible

com

-pu

ter,

an

optio

nal p

rogr

am is

ava

ilabl

e to

teac

h th

emab

out t

he p

rope

r de

sign

and

flig

ht c

onfi

gura

tions

of

2-lit

erbo

ttle

rock

ets.

Thi

s si

mul

atio

n pr

ogra

m w

ill h

elp

them

solv

e pr

oble

ms

like

dete

rmin

ing

the

prop

er d

esig

n fo

r a

nose

con

e an

d ta

il fi

n, te

stin

g th

e pr

oper

rat

io b

etw

een

fuel

cap

acity

and

wat

er p

ress

ure

for

max

imum

ran

ge, o

rde

term

inin

g th

e id

eal w

eigh

t for

a 2

-lite

r bo

ttle

rock

et.

Thi

s di

sket

te a

lso

cont

ains

a p

rogr

am f

or r

ecor

ding

and

anal

yzin

g la

unch

dat

a us

ing

2 lit

er b

ottle

roc

kets

.T

his

is a

mus

t for

lear

ners

inte

rest

ed in

per

fect

ing

the

de-

sign

of

thei

r 2

liter

bot

tle r

ocke

t. A

s le

arne

rs e

nter

dat

aba

sed

on th

e am

ount

of

wat

er a

nd p

ress

ure

used

for

eac

hla

unch

, inc

ludi

ng th

e tim

e it

took

fro

m la

unch

to la

ndin

g,th

e pr

ogra

m w

ill d

eter

min

e al

titud

e an

d sp

eed

of th

ero

cket

as

wel

l as

pred

ict i

deal

wat

er/p

ress

ure

ratio

s fo

rfu

ture

laun

ches

.

Pi5G

U55

i011

Exp

lain

to th

e gr

oup

that

they

are

now

goi

ng to

bui

ldan

d te

st th

eir

own

rock

ets.

Thi

s w

ill a

llow

them

to a

pply

wha

t the

y ex

peri

ence

d in

the

prev

ious

two

sess

ions

. Beg

inby

pro

vidi

ng g

roup

mem

bers

with

a d

emon

stra

tion

laun

chof

a 2

-lite

r bo

ttle

rock

et. T

he in

stru

ctio

ns in

this

sec

tion

prov

ide

you

with

all

the

info

rmat

ion

you

need

to d

esig

nan

d bu

ild a

suc

cess

ful 2

-lite

r ro

cket

.D

urin

g yo

ur d

emon

stra

tion

laun

ch, b

e su

re to

rev

iew

with

the

grou

p th

e W

arni

ng a

nd O

pera

ting

Inst

ruct

ions

that

cam

e w

ith th

e la

unch

er. S

tres

s th

e im

port

ance

of

"com

mon

sen

se"

arou

nd th

e ro

cket

s. J

ust b

ecau

se th

ero

cket

use

s a

"fri

endl

y" f

uel m

ixtu

re o

f w

ater

and

air

pre

s-su

re, d

oesn

't m

ean

they

igno

re th

e po

tent

ial d

ange

r of

the

rock

et u

nder

pre

ssur

e. T

his

disc

ussi

on s

houl

d al

so in

-cl

ude

an o

verv

iew

of

the

follo

win

g la

unch

pro

cedu

res:

3839

-Per

iodi

cally

che

ck th

e pr

essu

re w

ith a

tire

gau

ge.

Do

not e

xcee

d 14

01bs

of

pres

sure

Nev

er lo

ok d

own

on th

e ro

cket

dur

ing

or a

fter

pre

s-su

riza

tion

Nev

er a

im th

e ro

cket

at p

eopl

e, b

uild

ings

, or

othe

rst

ruct

ures

Alw

ays

set u

p th

e ro

cket

wel

l aw

ay f

rom

any

tree

sel

ectr

ical

wir

es, o

r bu

ildin

gsB

e su

re th

e la

unch

er is

fir

mly

fas

tene

d to

the

grou

ndB

e su

re to

hav

e an

aud

ible

cou

ntdo

wn

to z

ero

befo

repu

lling

the

laun

ch p

in.

Dem

onst

ratio

n La

unch

Is it

a R

ocke

t or

an E

ngin

e?Pr

epar

e to

laun

ch y

our

bottl

e w

ith n

o w

ater

and

abo

ut20

pou

nds

of p

ress

ure.

Thi

s sh

ould

be

done

with

the

plas

-tic

bas

e ca

p at

tach

ed to

the

botto

m o

f yo

ur b

ottle

. Fol

low

-in

g pr

oper

saf

ety

proc

edur

es la

unch

you

r bo

ttle,

then

.di

scus

s th

e fo

llow

ing

Gui

ding

Que

stio

ns w

ith th

e gr

oup.

Gui

ding

Que

stio

nsQ

. Did

the

bottl

e go

str

aigh

t up?

(ye

s)Q

. Did

it a

ppea

r to

be

stab

le?

(som

ewha

t)

If th

e gr

oup

coul

d an

swer

"ye

s" to

eith

er o

f th

ese

ques

-tio

ns th

ey p

roba

bly

coul

d th

ink

of th

e bo

ttle

as a

roc

ket.

How

ever

. try

fill

ing

the

bottl

e w

ith 2

5oz

of w

ater

and

pre

s-su

rizi

ng it

to 7

0 lb

s. A

fter

the

laun

ch, d

iscu

ss th

e sa

me

ques

tions

.

Gui

ding

Que

stio

nsQ

. Did

the

bottl

e go

str

aigh

t up?

(no

)9.

Did

it a

ppea

r to

be

stab

le?

(no)

Cha

nces

are

the

grou

p an

swer

ed n

o to

the

abov

e qu

es-

tions

. Wha

t the

y ne

ed to

rea

lize

is th

at th

e m

ore

thru

stth

ey a

pply

to th

e bo

ttle

the

less

sta

ble

it be

com

es: m

ak-

ing

it m

ore

like

an e

ngin

e in

nee

d of

a r

ocke

t.N

ow la

unch

a b

ottle

that

's b

een

prop

erly

des

igne

d to

perf

orm

as

a ro

cket

. Use

this

dem

onst

ratio

n as

a g

oal f

orth

e te

ams

to a

chie

ve o

r ev

en e

xcee

d. T

o ac

com

plis

h th

isgo

al, s

tart

by

phot

ocop

ying

and

dis

trib

utin

g th

e fo

llow

ing

"Roc

kets

Aw

ay"

sect

ion

to g

roup

mem

bers

. Thi

s se

ctio

nw

ill p

rovi

de th

em a

ste

p-by

-ste

p pr

oces

s fo

r bu

ildin

g a

succ

essf

ul r

ocke

t whi

le a

pply

ing

the

prin

cipl

es le

arne

d in

earl

ier

less

ons.

Enc

oura

ge te

am m

embe

rs to

kee

p a

jour

-na

l of

thei

r ob

serv

atio

ns.

Eva

luat

ing

Per

form

ance

Onc

e th

e te

ams

have

gat

here

d so

me

initi

al d

ata

onth

eir

rock

et's

per

form

ance

, get

them

bac

k to

geth

er f

orso

me

disc

ussi

on. 1

-lav

e ea

ch te

am p

rese

nt th

eir

find

ings

toth

e gr

oup.

To

high

light

thei

r fi

ndin

gs, y

ou m

ay w

ish

toha

ve e

ach

team

poS

t the

ir b

est l

aunc

h re

sults

on

an e

n-la

rged

ver

sion

of

the

"Rec

ord

of P

erfo

rman

ce"

char

t fou

ndon

pag

e 25

. Onc

e th

e te

ams

have

rep

orte

d, le

ad th

em in

adi

scus

sion

usi

ng th

e fo

llow

ing

ques

tions

.

Doe

s m

ore

wat

er m

ean

bette

r pe

rfor

man

ce?

Doe

s m

ore

air

mea

n be

tter

perf

orm

ance

?W

hy d

id s

ome

rock

ets

fly

bette

r th

an o

ther

s?W

hat h

appe

ned

whe

n no

wat

er w

as u

sed

tola

unch

the

rock

et?

If y

ou p

lotte

d th

e pe

rfor

man

ce o

f yo

ur r

ocke

tat

701

bs o

f pr

essu

re w

ith v

aryi

ng a

mou

nts

ofw

ater

, wha

t wou

ld b

e th

e sh

ape

of th

e cu

rve?

Und

er th

e sa

me

cond

ition

s, w

ould

this

cur

velo

ok d

iffe

rent

ly a

t dif

fere

nt p

ress

ures

?

Ext

endi

ng th

e Le

arni

ngT

ime

perm

ittin

g, h

ave

the

grou

p co

mpl

ete

the

Dig

ging

Dee

per

and

Goi

ng B

eyon

d se

ctio

ns o

f th

e ha

ndou

t. T

hese

sect

ions

are

des

igne

d to

lead

team

s to

fur

ther

exp

erim

en-

tatio

n w

ith th

eir

2-lit

er b

ottle

roc

ket.

0

Let

's G

etB

uild

ing

As

you

obse

rved

fro

mth

e in

itial

dem

onst

ratio

ns,

as th

rust

fro

m th

e bo

ttle

incr

ease

d, th

e le

ss s

tabl

e th

ero

cket

bec

ame;

mak

ing

it m

ore

like

an e

ngin

e in

nee

d of

a ro

cket

. Thi

s re

actio

n is

sim

ilar

to th

e re

leas

ing

of a

nin

flat

ed b

allo

on. T

o im

prov

e pe

rfor

man

ce, y

ou m

ust f

irst

over

com

e th

e fo

llow

ing

prob

lem

in y

our

rock

et's

des

ign:

Che

ck li

et

Cen

ter

of p

ress

ure

too

clos

eto

the

cent

er o

f gr

avity

.T

oo m

uch

resi

stan

ce to

win

d.

PR

OB

LEM

1C

ente

r of

Pre

ssur

e to

o C

lose

to th

e C

ente

r of

Gra

vity

Mat

eria

ls: 2

-lite

r so

ft d

rink

bot

tledu

ct ta

pe2

2 1/

2" (

outs

ide

diam

eter

), a

t was

hers

card

boar

dsc

isso

rs

Step

1: O

ne w

ay to

cha

nge

the

cent

er o

f gr

avity

of

anob

ject

is to

incr

ease

its

leng

th. J

ust l

ike

you

did

with

the

ballo

on r

ocke

t. H

owev

er c

ente

r of

gra

vity

can

als

o be

chan

ged

by a

ddin

g w

eigh

t to

one

end.

To

do th

is, a

ttach

(with

duc

t tap

e) tw

o 2

1/2"

(ou

tsid

e di

amet

er)

flat

was

h-er

s, o

r an

equ

ival

ent o

f 6o

z, to

the

roun

ded

end

of y

our

bottl

e. B

e su

re to

rem

ove

the

plas

tic b

ase

cap

(if

any)

be-

fore

atta

chin

g th

e w

ashe

rs to

you

r bo

ttle.

Step

2: O

nce

in p

lace

, tes

t you

r ro

cket

's c

ente

r of

grav

ity. D

o th

is b

y se

eing

whe

re it

bal

ance

s al

ong

your

fin

-ge

r. O

nce

dete

rmin

ed, m

ark

that

spo

t on

the

rock

et w

ith a

piec

e of

tape

. Now

test

. the

roc

ket's

cen

ter

of p

ress

ure

bycu

tting

a s

ilhou

ette

of

the

rock

et o

ut o

f ca

rdbo

ard

and

bal-

anci

ng it

on

your

ling

er. T

he p

oint

whe

re th

e si

lhou

ette

bala

nces

is y

our

rock

et's

cen

ter

of p

ress

ure.

(R

emem

ber,

the

dist

ance

bet

wee

n th

e ce

nter

of

grav

ity a

nd c

ente

r of

pres

sure

sho

uld

be n

o cl

oser

than

one

-hal

f th

e di

stan

ceeq

ual t

o th

e la

rges

t dia

met

er o

f th

e bo

dy.]

Exp

lana

tion

The

mas

s of

the

was

hers

at t

he to

p of

the

bottl

e m

oves

the

bottl

e's

cent

er o

f gr

avity

aw

ay f

rom

its

cent

er o

f pr

essu

re. B

ecau

se th

e m

ass

of th

e w

ashe

rs is

safe

ly a

way

fro

m th

e ro

cket

's c

ente

r of

pre

ssur

e, th

e w

ash-

ers

tend

to "

pull"

the

rest

of

the

rock

et b

ehin

d th

em.

PR

OB

LEM

2: T

oo m

uch

resi

stan

ce to

win

d

Mat

eria

ls: 2

-lite

r so

ft d

rink

bot

tlesc

isso

rsex

acto

-typ

e kn

ife

8"x8

" co

rrug

ated

car

dboa

rddu

ct ta

pebo

bby

pins

rule

r

The

re a

re tw

o fa

ctor

s to

con

side

r w

hen

talk

ing

abou

t win

d re

sist

ance

; dra

g an

d tu

rbul

ence

. Dra

g is

caus

ed w

hen

the

surf

ace

of th

e ro

cket

res

ists

the

flow

of

air

mov

ing

over

its

surf

ace.

If

you

rem

oved

the

labe

l fro

mth

e bo

ttle,

and

tape

d sp

arin

gly,

you

sho

uld

enco

unte

rm

inim

al d

rag

on th

e su

rfac

e of

you

r ro

cket

. Tur

bule

nce,

on th

e ot

her

hand

is c

ause

d w

hen

irre

gula

rly

shap

edsu

rfac

es o

r fe

atur

es tr

ap th

e fl

ow o

f ai

r m

ovin

g ac

ross

the

surf

ace

of th

e ro

cket

. Let

's tr

y fo

cusi

ng o

ur a

ttent

ion

on d

ecea

sing

the

amou

nt o

f tu

rbul

ence

cau

sed

by th

ero

cket

's d

esig

n.St

ep 1

: Ins

pect

you

r ro

cket

for

any

like

ly c

ause

s of

4243

turb

ulen

ce. W

hat s

houl

d co

me

to y

our

imm

edia

te a

tten-

tion

is th

e ir

regu

lari

ty c

ause

d by

the

atta

chm

ent o

fw

eigh

t to

your

roc

ket's

nos

e se

ctio

n. T

his

is a

n ob

viou

sge

nera

tor

of tu

rbul

ence

. To

corr

ect t

his

prob

lem

, fas

ten

a no

se c

one

to y

our

rock

et.

Thi

s ca

n be

don

e by

cut

ting

the

roun

ded

botto

m f

rom

an-

othe

r 2-

liter

bot

tle a

ndat

tach

ing

to th

e en

d of

you

rro

cket

. Thi

s w

ill h

elp

soft

enth

e fl

ow o

f ai

r ov

er th

e to

p of

your

soc

ket.

Just

be

sure

tosc

rape

off

any

hot

glu

e th

atm

ay h

ave

rem

aine

d af

ter

you

rem

oved

the

bottl

e's

plas

ticba

se c

ap.

Did

You

Kno

w E

ver

won

der

wily

are

al r

ocke

t has

a p

oint

ed n

ose?

It i

s to

prov

ide

stab

ility

as

the

rock

et b

reak

sth

e so

und

barr

ier.

How

ever

, the

bes

tno

se c

one,

des

ignf

or a

low

vel

ocity

mod

el r

ocke

t is

a ap

arab

le.

Step

2: N

ext,

cons

ider

the

neck

of

your

2-l

iter

bottl

ero

cket

as

a po

ssib

le c

ulpr

it of

turb

ulen

ce. W

hat d

o yo

uth

ink

happ

ens

once

the

air

flow

ing

alon

g th

e su

rfac

e of

your

roc

ket r

each

es th

is p

oint

? A

s th

is r

ush

of a

ir c

omes

toge

ther

at t

he n

eck

end

of th

e bo

ttle

itdo

es s

o in

a s

wir

ling

mot

ion,

cau

sing

the

base

to s

wiv

el a

s w

ell.

To

cont

rol t

his

mov

emen

t, tr

y ad

ding

fins

to th

e ba

se o

f yo

ur r

ocke

t. T

his

will

also

ass

ure

that

any

def

lect

ing

forc

es o

nth

e ro

cket

's n

ose

cone

will

be

coun

terb

al-

ance

d by

the

by th

e ae

rody

nam

icst

abili

ty o

f th

e ta

il fi

ns. (

Just

as

fins

wer

ead

ded

to s

tabi

lize

the

botto

m o

f yo

ur b

al-

loon

roc

ket.)

Air

flo

w

Thi

nk o

f a

way

for

the

nose

con

eto

pop

off

on

dece

nt, r

elea

sing

apa

rash

ute

or s

trea

mer

. Rem

embe

r,yo

ur r

ocke

t. w

ill b

e ac

cele

ratin

gba

ck to

ear

th a

t a v

eloc

ity o

f32

fee

t/sec

ond.

44

Whe

n pr

oper

ly d

esig

ned,

the

defl

ectin

g fo

rce

upon

the

nose

of

the

rock

et is

cou

nter

bala

nced

by

the

aero

dyna

mic

for

ces

on th

e fi

ns.

Step

3: B

uild

ing

Tai

l Fin

sU

sing

an

exac

to-t

ype

knif

e an

dth

e pa

ttern

on

the

follo

win

g pa

ge, c

utou

t thr

ee ta

il fi

ns f

rom

an

8"x8

" pi

ece

of c

orru

gate

d ca

rdbo

ard.

Be

sure

the

patte

rn is

pla

ced

para

llel t

o th

e co

rru-

gate

d "r

ibbi

ng"

of th

e ca

rdbo

ard.

Onc

e cu

t, sp

lit o

pen

the

1" s

ectio

n of

card

boar

d th

at e

xten

ds b

enea

th th

etr

iang

ular

por

tion

of th

e fi

n. W

hen

open

ed, t

his

port

ion

shou

ld b

e at

ari

ght a

ngle

to th

e fi

n.

RO

CK

ET

S IA

WA

Y I

Nex

t, ta

ke tw

o bo

bby

pins

and

ben

dth

em in

to th

e sh

ape

of a

'T'.

Mak

e su

reth

e to

p of

the

-T"

is a

t lea

st 1

1 /2

"w

ide.

Ins

ert t

he tw

o bo

bby

pins

into

one

of th

e tin

s so

that

the

"T"

por-

tion

of th

e bo

bby

pin

rest

s ag

ains

tth

e ex

tend

ed p

ortio

n of

the

fin.

The

hob

by p

ins

are

used

to s

tiffe

nth

e fi

ns d

urin

g fl

ight

. Rep

eat t

his

step

for

eac

h fi

n.O

nce

com

plet

ed, m

ount

you

rfi

ns w

ith d

uct t

ape

to y

our

bottl

e as

sho

wn.

(B

e su

reyo

ur,/i

ns a

re p

rope

rly

alig

ned

and

spac

ed. T

he b

otto

mof

you

r fi

ns s

houl

d be

abo

ut 3

" aw

ay f

rom

the

"ope

n"en

d of

you

r bo

ttle.

)

Fin

s, to

pvi

ew

---

Fin

s, s

ide

view

Fin

pat

tern

:

ar 0

Cor

ruga

ted

card

boar

d "r

ibbi

ng"

dire

ctio

n

4"

4"

4647

Mov

ing

Upw

ard

Bef

ore

you

begi

n to

test

the

initi

al p

erfo

rman

ce o

fyo

ur r

ocke

t, yo

u m

ost l

ikel

y w

ill w

ant a

sta

ndar

d fo

rco

mpa

riso

n. T

he b

est m

easu

res

of p

erfo

rman

ce a

re a

lti-

tude

and

vel

ocity

. You

r ch

alle

nge

is to

com

e up

with

are

liabl

e m

etho

d fo

r ob

tain

ing

this

dat

a. T

his

lead

s yo

u to

your

last

pro

blem

bef

ore

lifto

ff.

PR

OB

LEM

3-

Mea

surin

g th

e al

titud

e an

dve

loci

ty o

f you

r ro

cket

Mat

eria

ls: C

alcu

lato

rO

ne m

etho

d of

fin

ding

out

how

hig

h yo

ur r

ocke

tw

ent i

s to

tim

e th

e in

terv

al in

sec

onds

bet

wee

n la

unch

and

land

ing.

Onc

e kn

own,

you

can

det

erm

ine

the

alti-

tude

of

you

rock

et u

sing

the

follo

win

g fo

rmul

a H

=16

(t/

2)2:

whe

re H

is th

e al

titud

e, a

nd t

is th

e tim

e in

sec

onds

.Fo

r ex

ampl

e, le

t's s

ay it

took

4 s

econ

ds f

rom

laun

ch to

land

ing.

You

wou

ld f

irst

. div

ide

4 by

2. w

hich

wou

ld g

ive

you

2. Y

ou w

ould

then

squ

are

2. g

ivin

g 4

(you

squ

are

anu

mbe

r by

mul

tiply

ing

it by

itse

l f),

and

mul

tiply

ing

this

by 1

6. I

n th

is e

xam

ple.

you

r ro

cket

wou

ld h

ave

reac

hed

an a

ppro

xim

ate

heig

ht o

f 64

fee

t.T

o de

term

ine

your

roc

ket's

vel

ocity

, tak

e th

e nu

mbe

rof

sec

onds

it to

ok f

rom

laun

ch to

land

ing

and.

divi

de it

by 2

. The

n ta

ke th

e he

ight

that

it tr

avel

ed a

nd d

ivid

e it

by th

e nu

mbe

r of

sec

onds

you

just

cal

cula

ted.

Thi

s w

illgi

ve y

ou a

num

ber

calle

d "f

eet p

er s

econ

d". T

o co

nver

tth

is n

umbe

r in

to m

iles

per

hour

mul

tiply

it b

y 0.

68.

Usi

ng th

e fi

rst e

xam

ple,

the

rock

et to

ok 4

sec

onds

from

lift

off

to la

ndin

g. N

ext.

divi

de th

is n

umbe

r by

2w

hich

wou

ld g

ive

you

2 se

cond

s. Y

ou w

ould

then

take

the

heig

ht it

trav

eled

(64

fee

t) a

nd d

ivid

e it

by 2

sec

onds

,gi

ving

you

a s

peed

of

32 f

eet/s

econ

d. M

ultip

ly 3

2 by

afa

ctor

of

0.68

and

you

get

an

aver

age

velo

city

of

21.7

6m

iles

per

hour

.

Let's

Get

Lau

nchi

ngPr

ocee

d to

the

laun

ch a

rea

with

you

r ro

cket

. Bef

ore

you

laun

ch o

bser

ve th

e fo

llow

ing

proc

edur

es:

Peri

odic

ally

che

ck th

e pr

essu

re w

ith a

tire

gau

ge.

Do

not e

xcee

d 14

01bs

of

pres

sure

Nev

er lo

ok d

own

on th

e ro

cket

dur

ing

or a

fter

pres

suri

zatio

nN

ever

aim

you

r ro

cket

at p

eopl

e, b

uild

ings

, or

othe

r st

ruct

ures

Alw

ays

set u

p yo

ur r

ocke

t wel

l aw

ay f

rom

any

tree

s, e

lect

rica

l wir

es, o

r bu

ildin

gsB

e su

re th

e la

unch

er is

fir

mly

fas

tene

d to

the

grou

ndB

e su

re to

hav

e an

aud

ible

cou

ntdo

wn

to z

ero

be-

fore

pul

ling

the

laun

ch p

in.

Try

sev

eral

laun

ches

at v

aryi

ng a

mou

nts

of w

ater

and

pres

sure

. A g

ood

plac

e to

sta

rt is

abo

ut 2

5 ou

nces

of w

ater

and

75

lbs.

As

you

laun

ch y

our

rock

et in

clud

ein

you

r ob

serv

atio

ns th

e nu

mbe

r of

sec

onds

fro

m la

unch

to la

ndin

g as

wel

l as

any

sign

s of

inst

abili

ty. U

se th

ech

art b

elow

to r

ecor

d yo

ur d

ata.

4849

pap.

Rec

ord

of L

aunc

hes

Onc

es o

fA

ir

Wat

erPr

essu

reH

eigh

tV

eloc

ity

Lau

nch

# I

Lau

nch

#2

Lau

nch

#3

Lau

nch

#4

Lau

nch

#5

Lau

nch

#6

Lau

nch

#7

Lau

nch

#8

Lau

nch

#9

Lau

nch

# I

0

50

Eva

luat

ing

Per

form

ance

Onc

e yo

u co

mpl

eted

you

r la

unch

es a

nd c

alcu

latio

ns,

reco

rd th

e pe

rfor

man

ce o

f yo

ur r

ocke

t in

the

char

t be-

low

. Sha

re th

is in

form

atio

n w

ith y

our

grou

p in

ord

er to

mak

e so

me

assu

mpt

ions

abo

ut h

ow 2

-lite

r bo

ttles

per

-fo

rm. W

hen

disc

ussi

ng y

our

data

, con

side

r th

e fo

llow

ing

ques

tions

:

Doe

s m

ore

wat

er m

ean

bette

r pe

rfor

man

ce?

Doe

s m

ore

air

mea

n be

tter

perf

orm

ance

?W

hy d

id s

ome

rock

ets

fly

bette

r th

an o

ther

s?W

hat h

appe

ned

whe

n no

wat

er w

as u

sed

to la

unch

the

rock

et?

If y

ou p

lotte

d th

e pe

rfor

man

ce o

f yo

ur r

ocke

t at.

701b

s of

pre

ssur

e w

ith v

aryi

ng a

mou

nts

of w

ater

,w

hat w

ould

be

the

shap

e of

the

curv

e?U

nder

the

sam

e co

nditi

ons,

wou

ld th

is c

urve

look

diff

eren

tly a

t dif

fere

nt p

ress

ures

?

51

Rec

ord

of P

erfo

rman

cePl

ot th

e am

ount

of

wat

er a

nd a

ir p

res-

sure

use

d fo

r ea

ch la

unch

alo

ng w

ith th

ehe

ight

ach

ieve

d. C

onne

ct th

ese

poin

ts f

orea

ch la

unch

usi

ng d

iffe

rent

col

ors.

Use

this

data

to im

prov

e yo

ur r

ocke

t's p

erfo

rman

ce.

Hei

ght

-600 575

-550

525

500

-475

-450 42

5

400

-375 35

0

-325 30

0

275

250

225

200

175

-150 12

5

100

-75

-50

-25

4036

3228

2420

1612

84

015

3045

6075

9010

512

013

5

ounc

es o

f w

ater

air

pres

sure

Pig

ging

Dee

per

Let's

Con

tinue

Bas

ed o

n yo

ur in

itial

laun

ches

, you

're p

roba

bly

won

-de

ring

how

to m

ake

your

roc

ket g

o as

fas

t as

poss

ible

.T

o do

this

you

nee

d to

con

side

r N

ewto

n's

seco

nd la

w o

fm

otio

n. T

his

is th

e la

w w

hich

say

s th

at in

ord

er to

in-

crea

se th

e ac

cele

ratio

n of

an

obje

ct y

ou e

ither

nee

d to

decr

ease

its

mas

s or

incr

ease

the

amou

nt o

f th

rust

use

dag

ains

t the

obj

ect.

The

refo

re, t

o in

crea

se th

e pe

rfor

-m

ance

of

your

roc

ket y

ou n

eed

to o

verc

ome

the

follo

win

gpr

oble

ms:

Che

ck li

stM

inim

izin

g th

e ro

cket

's w

eigh

tw

ithou

t com

prom

isin

g st

abili

ty.

Impr

ovin

g th

e ro

cket

's d

esig

n.

PR

OB

LEM

4 -

Dec

reas

e ro

cket

wei

ght

with

out c

ompr

omis

ing

stab

ility

.

The

bes

t way

to d

ecre

ase

the

wei

ght o

f yo

ur r

ocke

t is

to r

emov

e on

e of

the

was

hers

you

add

ed to

shi

ft th

e ce

n-te

r of

gra

vity

aw

ay f

rom

its

cent

er o

f pr

essu

re. H

owev

er,

with

less

"m

ovin

g m

ass"

you

may

incr

ease

the

rock

et's

susc

eptib

ility

to a

ir tu

rbul

ence

. You

.als

o ri

sk m

ovin

g th

ero

cket

's c

ente

r of

gra

vity

too

clos

e to

its

cent

er o

f pr

es-

sure

. Try

adj

ustin

g th

e w

eigh

t at t

he to

p of

you

rro

cket

whi

le m

aint

aini

ng s

tabi

lity

and

perf

orm

ance

.

54

PR

OB

LEM

5: I

mpr

ovin

g yo

ur r

ocke

t'sde

sign

Con

side

r th

e fo

llow

ing

fact

sw

hen

impr

ovin

g up

on y

our

rock

et's

des

ign:

Nos

e C

ones

The

sha

pe o

f th

e no

se c

one

has

a gr

eat e

ffec

t on

the

amou

nt o

f dr

ag th

at a

roc

ket e

xper

ienc

es. A

par

abol

icno

se c

one

crea

tes

the

leas

t am

ount

of

drag

. Ago

odle

ngth

to w

idth

rat

io is

thre

e to

one

.

80 60 40 20 0

55

Fin

e A s

wep

t bac

k fi

n cr

eate

s le

ss d

rag

than

a s

trai

ght o

rfo

rwar

d-sw

ept f

in. A

lso

roun

ded

corn

ers

on a

fin

cre

ate

less

dra

g th

an s

harp

cor

ners

.

Cen

ter

of G

ravi

ty

Ano

ther

alte

rnat

ive

to m

inim

izin

g th

e w

eigh

t of

anob

ject

whi

le m

ovin

g its

cen

ter

of g

ravi

ty a

way

fro

m it

sce

nter

of

pres

sure

is to

mak

e it

long

er; j

ust l

ike

the

Chi

-ne

se d

id w

ith th

eir

fire

arr

ows.

Sur

face

Smoo

th s

urfa

ces

caus

e le

ss d

rag

than

rou

gh s

ur-

face

s.

5657

S

Goi

ng b

eyon

d R

ocke

t Sta

ging

Mat

eria

ls: l

6oz

tall

plas

tic c

up2-

liter

bot

tle w

ith b

ase

cap

Hav

e yo

u ev

er w

onde

red

why

roc

kets

are

ass

embl

edin

sta

ges?

To

enab

le r

ocke

ts to

acc

eler

ate

to h

ighe

r el

-ev

atio

ns w

ith g

reat

er p

aylo

ads,

des

igne

rs m

ust m

inim

ize

the

rock

et's

mas

s w

hile

max

imiz

ing

the

amou

nt o

f fo

rce

exer

ted

from

its

engi

nes.

Thi

s is

typi

cally

acc

ompl

ishe

dby

igni

ting

engi

nes

in s

tage

s. T

his

allo

ws

depl

eted

en-

gine

s to

be

sepa

rate

d aw

ay f

rom

the

mai

n ro

cket

,th

ereb

y de

crea

sing

the

rock

et's

mas

s w

hile

incr

easi

ng it

sac

cele

ratio

n. T

ry th

e fo

llow

ing

activ

ity to

exp

lore

this

met

hod

furt

her.

Act

ivity

: Tak

e an

em

pty

2 lit

er b

ottle

, (w

ith it

s ba

seca

p in

pla

ce),

fill

it w

ith 2

0 ou

nces

of

wat

er, a

nd p

lace

iton

the

laun

cher

. Pre

ssur

ize

the

bottl

e to

50

lbs.

Now

take

som

ethi

ng li

ke a

pla

stic

spo

rts

bottl

e or

a ta

ll 16

ozpl

astic

dri

nkin

g cu

p. F

ill th

e co

ntai

ner

with

12

ounc

es o

fw

ater

and

pla

ce it

on

top

of th

e bo

ttle.

Now

, lau

nch

the

bottl

e an

d no

te w

hat h

appe

ns.

Exp

lana

tion

Wha

t you

sho

uld

have

obs

erve

d is

an

exam

ple

of r

ocke

t sta

ging

. Onc

e th

e bo

ttle

ran

out o

fth

rust

, its

red

uced

mas

s m

ade

it m

ore

susc

eptib

le to

the

forc

es o

f w

ind

and

grav

ity. H

owev

er, i

f yo

u no

ticed

the

wat

er f

illed

con

tain

er, i

t sho

uld

have

con

tinue

d to

clim

bju

st li

ke th

e se

cond

sta

ge o

f a

rock

et. T

his

is b

ecau

se th

eco

ntai

ner

had

mor

e "m

ass

in m

otio

n" (

kine

tic e

nerg

y)w

hich

allo

wed

it to

res

ist t

he f

orce

s of

win

d an

d gr

avity

for

a lo

nger

per

iod.

Thi

s ex

peri

men

t can

be

liken

ed to

atr

ain

trav

elin

g al

ong

side

a c

ar a

t 50

mph

. Alth

ough

bot

har

e tr

avel

ing

at th

e sa

me

rate

of

spee

d, th

e tr

ain

wou

ldta

ke a

lot l

onge

r to

sto

p du

e to

its

enor

mou

s m

ass.

58

Com

pute

r A

ssis

tanc

eFo

r gr

oups

with

acc

ess

to a

com

pute

r. a

n IB

M c

om-

patib

le p

rogr

am is

ava

ilabl

e to

ass

ist i

n pe

rfec

ting

your

2-lit

er b

ottle

roc

ket.

Thi

s si

mul

atio

n pr

ogra

m w

ill h

elp

you

solv

e pr

oble

ms

like

dete

rmin

ing

the

prop

erde

sign

for

a no

se c

one

and

tail

fin,

test

ing

the

prop

er r

atio

be-

twee

n fu

el c

apac

ity a

nd w

ater

pre

ssur

e fo

r m

axim

umra

nge,

and

det

erm

inin

g th

e id

eal w

eigh

t for

a 2

-lite

rbo

ttle

rock

et.

Thi

s di

sket

te a

lso

cont

ains

a p

rogr

am f

orre

cord

ing

and

anal

yzin

g la

unch

dat

a us

-in

g 2

liter

bot

tle r

ocke

ts. T

his

is a

mus

tfo

r gr

oups

inte

rest

ed in

per

fect

ing

the

desi

gn o

f th

eir

2 lit

er b

ottle

roc

ket.

As

data

is e

nter

ed b

ased

on

the

amou

nt o

fw

ater

and

pre

ssur

e us

ed f

or e

ach

laun

ch.

incl

udin

g th

e tim

e it

took

fro

m la

unch

tola

ndin

g, th

e pr

ogra

m w

ill a

utom

atic

ally

det

er-

min

e al

titud

e an

d sp

eed

of th

e ro

cket

as

wel

l as

pred

ict

idea

l wat

er/p

ress

ure

ratio

s fo

r fu

ture

laun

ches

:

59

0000000CCCCC'CC( CC( C C.CCCC CCCC,C CC( C.0 C C_( C C

4 P.1.1i

Ey

n

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