1. Momentum of an object is due to only the velocity of the object. Tor F?

"\

\ '

False. It also includes mass.

3. Lin omentum is thea. product of the mass an ve OCI 0 a moving objec

n I y 0 Ion use Wit objects rotating a out a fixed axisc. average force and the time interval over which it actsd. angular momentum and torque

'(K)

2. A small person could possibly have more momentum than a large person. T or F?

I?-u£~e smaller person could have more mass and/or more velocity that totals moremomentum.

301. I can identify momentum as the product of mass and velocity.

Chapter 9 - Momentum and its Conservation

303. I can analyze the momentum of a system of objects in one dimension.

4. You are gliding on ice skates and you throw a heavy ball forward. Like we have been practicingthis chapter, the system is:. a) You

b) The Bou and the Ball

c5. A 65-kg teacher rides their 8-kg bike during a triathlon. The teacher maintains an average bikingvelocity of 8.33 m/s for 6.5 hours. Find the teacher's momentum during the bike portion of the race.

a. 475 kg"m/s r5 ;:-M=Q II J(/\b. 541 kg"m/s ~ .f) .:- '<tOc.. ~. ~~'t\c. 608 kg"m/s r J ~d. 2,190 kg"m/s M:: 6\~t8~B. ~ 73&, teeuher~Vl-4JMeAt-lL,", ::::5~II~~

304. I can distinguish between elastic ~~ in'ePas~~collisions\La..ck'L"- t b ~be j\!\..OM.U\r-L.l."'-1.:-?08j,.s

6. What is the difference between an elastic collision and an inelastic collision? (Note: technically, weare talking about a completely inelastic collision. Up to now we've been calling it just an "inelasticcollision", whi is not the pro er n 't

A comp etely Inelastic collision is where the objects stick together; an elastic collision isbounce off without losing any kinetic energy

omen um ISnot conserved for completely InelMtlc co ISlons, ut It ISconserve forelastic

c) Momentum is not conserved for either type of collision

A.

9.1.Calculate momentum of individual objects as well as of a system of objects

7. The standard unit for momentum is the kg*m/sec. T or F?

-'>. .> \'\JA:~ ~ ~ rv-aHTrue. ~M-o,

~ M~ : 1Je..(o,,-I':)8. Which has more momentum: a bullet (m=0.1 kg) travelling 1,000 mls or a motorcycle (m=100kg)travellin Is?

a

A. (100 kg mls for bullet vs. 50kg mls for motorcycle)

9.2.Explain connection between Newton's 3rd law and conservation of momentum (perhaps makingrigorous using impulse-momentum theorem)9.3.Use conservation of momentum to solve various problems

600~~~t'E jaj/~~:~Joo~•..~

A. He will be moving slower, but he will still be moving forward with a momentum of300kg m/s.

9. A young man is moving forward on roller-skates with a momentum of 600 kg'm/s when someonethrows a cannonball from in front of him. He catches the cannonball, which initially had a momentumof -300kg'm/s. What will happen? (think about whether he has positive or negative momentum afterthe collision)~ -- ..::.

a. He will be moving forwaIb ~~M.'r, t ~l..b. I stop.c. He will be moving backward.

"Cart Explosion"

10. Gaston and Belle are standing together on an ice rink (at rest). Gaston proposes to Belle, andshe refuses. Suddenly, he pushes her away, and they both begin moving in opposite directions. Belleis gliding away with a velocity of +3m/s (to the right). Gaston's mass is 140 kg and Belle's mass is60kg. What is Gaston's momentum after the explosion? (Hint: this problem is not extremelycomplicated) 'flt\ ':: l 61'£. !<I~ .• (r 01" \( 3""'\~1-1 r;,,"~

a)-60kg'm/s P'L~rr~O S '" D":,) '1'\ \~-:v\...:;(0"~b)-180kg'm/s -= ~"\-':.\!ibli.« ~ -\roOI ,.1c)-520 kg'm/s ....J 1.. ~ /J

,- 1'<\.\.),£-1' ~'l..lh.{ 1>lf =-+5'if'kB. Must be the equal and 0 posite Belle's. The total momentum must be zero.

-I,r~

The

l'\:i.l" t 1V\1 i.l~\~ fII,\ll,~ ,. I\~'Olf.M\l),i. t M."V~, ':0 0\. 'f-"'t)Vp.

()~ 't" ~,Vl't Mol V1.:fI\, b\\t..)

Sticking "inelastic"11. A child throws a 0.50kg piece of putty with a velocity of 6 mls at a stationary 1.5kg toy truck.putty sticks to the truck. What is the final velocity of the puttyltruck combo?

a) 6m/s _b)12m/s tv\\ ~0, 51j "Ut,.-=O ~.\ '" ~~

~ ""V,i.~'MtJ~ 'M.~~\.~~ (V\

D. Total momentum remains the same (3.0kg m/s)

Bouncing "elastic"12. A large (1.0kg) glider moving +3m/s slams into a small glider (0.25kg) going -4m/s in the oppositedirection. The final velocity of the large glider is positive 1.5 mis .What is the final velocity of thesmall gli

a)+2m/s ~r~p.:.\'1\,1.>,'\ 't" \'1\ •..1)1-~ '::: t-\;Utl f M"t '"OLf- ms \ M "',:t M. .•.Vll' -M,7J,f

c)1.5m/s l"V' ~ 1l\l::HS"~~ 1)2.+-- ~,_V_. -e) 0.5m/s IV-'; ()J.&~ -J z.t ~ 7. (1/\"1-

ll'::, ,:,"\'B--. ~ ~'':l~-~~~ [ + 2. (¥.Ls J

9.4.Recognize conditions of validity for conservation of momentum (no external forces acting on thesystem)

13. The law of conservation of momentum states that . I'V\ u.~r~r;Sa.~a. momentum can be increased and decreased if it is not too great q- eo".// be.-b. the momentum of any closed system that doesn't lose or gain mass does not chang#'" qtuofl.t.jc. the mome.D!lliJLof-any ystem..dQ..esnot change (-0 'X.ed. e momentum of any closed system wit no ex ernal force does not change ~

o9.5.Calculate impulse14. Before a collision, a 50.0-kg object is moving at +5.0 m/s. Find the impulse that acted on theobject if, after the collision, it moves at +8.0 m/s. =:PfII.J- _ I ( _/\....a. 4.5kgom/s ti'-"~k 'L\v- M.PI./.- ~e.- -""ttlb. -4.5 kgom/s:.J ~ Ic. -1.5x102kgom/s \)r-e"'~ \""~U1-St: -: ""-Vr-1'\1)~-;;L(;zJft:,,%.OI"Ud. 1.5x10

2kgom/s -tj;.~~"fJ :: 1.)6~

o ~

::: lY\ 1) f - M:V,

~ G 1s1!1~({))-[(jl(~J(jL"~

IY I b2.( ~ft'bI ~6Ou ~Mf>

tf\- ::1Kit ~1\::.2..7 I'\~\)~ ~ \21'1(5A

15. The velocity of a 975-kg car is changed from 12.0 m/s to 27.0 m/s in 15.0 s by an external,constant force. What is the resulting change in momentum of the car?a. 1.46x 104 kgom/sb. 9.75x102 kgom/sc. 2.19x 105 kgom/sd. 7.22x104 kgom/s

16. Analyze the graph. Which quantity is equal to the impulse?

1.5 x 10'

-1.5 -1.0 -0.5 0 0.5 1.0 1.5

time (milliseconds)

a. time of collisionb. distance along curvec slod. area under the curve

D. The area would equal F x t which is the impulse.

.: -Of - V~::A1)

r:-'-I,)~fvt..::-l ,2. r~LA i..:: 16.0:.

A

9.6.Use impulse-momentum relation to solve problems17. A constant force of 4.5 N acts on a 7.2-kg object for 10.0 s. What is the change in the object'svelocit ?

6.3 ml3. mls

c. 1.2 mlsd. 4.33 mls

FAt ~A P " tv\ 1)( - M V\'

f4t[VI.

~::rb,2r; ~j1.2. ICj ----

18. The velocity of a 975-kg car is changed from 12.0 mls to 27.0 mls in 15.0 s by an external,constant f at is the magnitude of the force?

a. 9.75x102

f'I'~lJ1-) fA-t: 6.pb.C. 9.75x103 N Vi.' 12"'~ ~::. ~ _ "fr\l-¥-"'Wd. 975 kg'~s "Uf' 'l...71{~ til At.

~~~<.t L\t:(~,Os :: f57) ~;"0-7M/&-rt7G/Jjl-1(Jl[ pr11pplv conservation of momentum in two-dimensio~al problems for simple problems. even if onlv

conceptual9.8.Analyze various real.life applications of momentum & impulse

A moving Semi.Truck slams into a compact car moving in the opposite direction.19) The impulse on the compact car is the same as the impulse on the truck. Truel False

True - Newton's 3'd law says forces are the same. Times must be the same, so same.

20) The force is the same magnitude on both True! False

True - Newton's 3rd law says forces are the same. Times must be the same, so same.

21) The change in speed is the same magnitude True! False

False - The change in momentum is the same, but the change in speed would dependon the masses.

22) The change in momentum is the same magnitude True! False

True - If it is a closed, isolated system, the changes in momentum would be the same.

23. A bicycle and a parked car have a head-on-collision. The force of impact is greater on the bicycle.Tor F?

False - Newton's 3rd law says forces are the same. Times must be the same, so same.

24. An automobile dashboard that is padded would lengthen the time of impact more than anunpadded dashboard in case of a collision.

Tor F?

True - It would slow you down over a longer period of time.

25. When a stationary rocket fires its engine the rocket has the same amount of momentum as theexhaust of the rocket.

Tor F?

True - It will move much slower, but it has the same momentum.

26. Two gliders having the same mass and speeds move toward each other on an air track and sticktogether. After the collision the velocity of the gliders is:

a. twice the original velocityb. the same as the original velocityc. one half the original velocityd. zeroe. not enough information to say

D. Total momentum at the beginning is zero, therefore momentum at the end must bezero.

27. In order to catch a ball, a ball player moves their hand backward in the direction of the ball'smotion. Doing this reduces the force of impact on the player's hand primarily because:

a. the velocity of impact is reducedb. momentum of impact is reducedetime of Impact is increas~

thP timB of-impact is decrea ~

c

28. A cannonball shot from a long-barrel cannon travels faster than one shot from a short barrelcannon because the cannonball receives a greater

a. fo. im uls

c. -oth a and bd. neither a or b

B - longer time for the applied force

9.9 I can explain what impulse is and its relationship with change in momentum29. The ct of the average force and the time interval over which it acts is the _a. impulseb. ve ocityc. accelerationd. linear momentum

A. It also equals the change in momentum, but it is called impulse.

Linear Momentum

A P ~ I'l\ VI - "'''VI'

7 (o:~-l{~)-[~'~J~~~ -/7. (, IY'/J

Answer: (a) 18. kg mlsDiff: 3

3) A 0.32 kg ball is moving horizontally 30. mls just before bouncing off a wall, thereafter moving25. mls in the opposite direction. M..-= 6."':.2 1<

(a) What is the magnitude of its change in momentum? lJ . _ 1. ~ I,,- .JO '!.

lJL"" - LS-"~

Answer: C (Remember the bullet changes directioD~2 ~ft -s,2.

P.: .

!'fI '= IOO~~ 0.100#5

lI.,j ':--\2 M,

~

'I -o~:OIL I lJ1: ::: IC).?' 7

Answer: A I f, __ 0 " 't f)Diff' 2 "1.- -I:U 1{2. 6

. ~ ::"'-IJ ~ 0 .lOO~(lr. )rs) I. sJ~lI6) A bullet of mass 20. g, traveling at 350. mis, strikes a steel plate at an ang~ of30.0 with the plane of the plate. It ricochets off at the same angle, at a speed of320. m/s. What is the magnitude of the impulse that the wall gives to the bullet?

A) 0.52 N.s r'rI •.. 0, 02..0 ~ O{' M1Jf'''~.Oz.L.~)tUJ~'B) 4.3 N.s , - I ulifj U'C) 6.7 N.s \)\ -= 3,W ~ e to _ 'b,l ISe 120"D) 0.30 N.s -0 '3.LO"'I LOP '- - (6,11201,,)(J:r-, )E) 0.30 kN.s V I!<? I 0 -7 ~ Cl o~

- '..'J "I-

rill.: 4 f ~pi -PI. {;o.5~

- S,S .10- b,:r - 0.6

5) A ball. of mass 100. g. is dropped from a height of 12. m. Its momentum when it s rikes theground is

) 1.5 kg.m/s ..m s.

C) 3.3 kg.m/s.D) 2.4 kg.m/s.E) 1.8 kg.m/s.

An Olympic diver dives off the high-diving ptatform.

c

1\\= S~

Answer: ADiff:2

8) The magnitude of his momentum will be a maximum at which point (A, S, C, or D)?A)AB)B

~

Answer: 0o iff: 19) After leaving the platform, the diver's momentum will be least at which point?

~~ V::() ar

Answer: BDiff: t....---10) A handball of mass 0.10 kg, traveling horizontally at 25. mIs, strikes a wall and rebounds at19.m/s. What is the change in the momentum of the ball?

A)0.60kgm/s I\~_I M~I -('1\.1)B) 72 kg m/s ('/\:: Od'O (0. '-\~ -. :::- (" vf lC) 1.2 kg m/s f. "C,D) 1.8 kg m/s l)f.~ -\q"(~ _ '''If,I0ff:1~1J -f~p./~J..2r'0E) 5.4 kg m/s -U, ""-20'S "'~' ~

- - 6,~0 ~ is

Answer: ADiff: 1

Answer: 0Diff: 2

12) A 1200. kg ferryboat is moving south at 20.m/s. Its momentum isA) 1.7 X 10-3 kg mls M.- (U)()B) 2.4 x 103 kg.m/s 2-t.{OOj"{j [).: 1y'\,V "'1J ~ o~t~C) 1.2 x 103kg.m/s f - Zc i.s

1DJ}4,OO[kQ mJ~ p:: !fZOO ,...' \~ 6.0 x 102 kg.m s ~ to Ii.,)

~ 2.- 4,0 00 ~ ""/J

Choose from the following list:(a) pound(b) slug-ftIs(c) centimeter(d) kg mls(e) newton

,••

13) An SI unit of !:J.p/!:J.t is which one of the choices above?

F; M..L\tAnswer:{;;J Newton (Dlff:1

14) An SI unit of momentum is which one of the choices above?

Answej(d) kg mls ]Dlff: 1 L----

osed and isolated" ystem; i.e., if the net external force

. - ~ (\ () (0(( or a.dJlh'o,,- tJ~ ~.srID I\et C)(~UM) (:O/le..

Answer: Momentum is conserved for a 'acting on the system is zero.

.A~:: Pf - p,' -:._rA -U f - M 1) "

fiOk'} f!S 'YJJ -&O~){~"VJ1) Daisy (50. kg mass) skates on ice at 4.0 mls to greet her friend (70. kg mass), who is standing still,with open arms. As they collide, while holding each other, with what speed do they both move offtogether?

A) 2.5 mls\~{ 1.7 m/s]

zeroD) 5.0 mls

Answer: FALSE175kg m/s)Diff: 2

15) A 1.0 kg cheese-ball vertically falls and strikes the floor with a speed of 20.m/s, and it bouncesstraight up with a speed of 15.m/s. The magnitude of its change of momentum is 5.0kg-m/s.

tJ\== -2.0 ""& --0" If""!:(remember it changes direction. Momentum is a vector. The magnitudt would1Je

Impulse

3) A .050 kg beach ball approaches at 6.0 m/s. A player hits it directly back with a speed 7.0 m/s.(a) What was the momentum change (magnitude) of the ball?(b) If the contact time was 0.040 s, what was the average force on the ball during contact?

~, .... ,_ "" - D 1"l:J"( 1\ p: MV( -MVcAnswer: (a) ?~ ..,-. V:>~ '-\ f/ ,\II. 7Diff: 3 (b) ~s 1J,"~~'O,/J -:.[g..Or()~J.-7,(;'Yj~",CW~!b.()rljJt-O.6S'~.t6

1ft - 7.()'IJ 4f4t-4P I=-e£. ~-a.6S'4:f(5) Two cars suffer a head-on collision. What is conserved in the collision? -C\C o.o'{o (f

A) mechanical energy and momentum t'ti ! I / 3 3-(B) kinetic e er y •.. T~R..N rcJ /-t (; 1 •••E_..;;b..:., .::...:..:fV:.....;.

mo tu !01olV'O , Ll"rtrneither energy nor momentum is conserved)

Answer: CDiff: 1

f; ::0

f 'fO .::. ()I( r 4PI\. -=: - pl.1.

•,.Answer: ADiff: 2

6) An 80. kg man is skating Northward and happens to collide with a 20.kg boy who is ice skatingtoward the East. Immediately after the collision, the man and boy are seen to be moving together at2.5 m/s in a direction 60 degrees North of East. Ho~ast was the boy moving b~f.?re the collision?

Answer:6.3m/s p,h p,tP~=P1 = @O~JvJ+-[za~(VL~=lW\.h~~}~..r~~o"Dlff:2 V Pt f .(so~-t\(~~Mo= Izr~"'b : 2.50 ~,,~e-60&J

iy 0+- ,fiSD "I,\1.irJd)' •. Z.14~~ - -7) An empty coal-car (mass 20,000.kg) of a train coasts along a 10.nils. An unfortunate 3000.k~elephant falls from a bridge and drops vertically into the car. Determine the speed of the car lk.immediately after the elephant is added to its contents. \1/Z/:: Zop,p"tJ!fJ "Is C/'

"',~" < M,V'I C .•1''''''9 >..to; 0 ,Answer: 8.7 m/s ::- flor 2HDlff:2 0AOO~''j) O"~)=&-O''''''(;'!:JtjPaPlr;l"4.f) 8.7~ r~= 1}.S1/Mh @.8) A 3. kg ball of putty moving at 1.m/s collides and sticks to a 2.kg ball initially at rest. The putty aR'cf.=Jball then move with a momentum of p,:. f~

A) 1 kg m/s. ltI. -::~ ~B) 2 kg m/s j til l.J t ..vi •v.,' ": /II ,v'I I ,t 111• V,.C ~ kg ~~:': ~1.,2~~M/( '~~~'~~;';&~LD~~)~ 3 ~~ifE) m s. ./

() N ("(\ "1) 1-l -:: /"Answer: D J

Diff:2 ..-"1 , VV2f - If

9) Two cars collide head-on on a level friction-free road ..The collision was completely inelastic andboth cars quickly came to rest during the collision. What is true about the velocity of this system'scenter of mass?0) It was alWays zero)

's, It w~s I level zelo.C) It was not initially zero, but ended up zero.

Answer: AOiff:2

10) A Ping-Pong ball moving East at a speed of 4 mls collides with a stationary bowling ball. ThePing-Pong ball bounces back to the West, and the bowling ball moves very slowly to the East. Whichobject exp-eriences t ate nitude im ulse durin the collision?

A) neither; both ex erienced the same magnitude impu 4 p=:I tip (J..Lts;e..I s Impossl he Veloclttm>crfter-th ision are unknown

C) the bowling ball for Q c...(()se./ I0) the Ping-Pong ball ~ •.. I /~(a.jeoj~{ell.\. 7

4p::= 0

~ IY1 ,11'1 t II\.'"V~f

-,:.~, tM:)V'i-

Answer: 14.3 mlso iff: 2

11) A car (mass = 1500 kg) and a small truck (mass = 2000 kg) collide at right angles at an icyintersection. The car was traveling East at 20 mls and the truck was traveling North at 20 mls whenthe collision took place. :i ~dd J 1.t!pGf If M ,1),,'=- (~I~ZO't': I 3'.I;'I

1"\,'_lSW~ p~~:J\l.~,: 'fOIt#/j...•1J ~fo. .S'S"''h - UXl()~ -*)v1) .: lO"'II@jf -<:::>"

Ie car-Vt~ ":2..Owlk e fOo ;X { R f l: 'R/r R..:j~

I~y 3",o()(1 truck f ¥-::- <5",tl"O f H'ftJ,t.W~,e.u.c.1L 0 '(O,DtJo -' Cl

34tW Va, aJJ •... 5 OJ~ ~t v.::. ~What is the speed of the combined wreck, assuming a completely inelastic collision? : rt?"&ll:Jot'li

Ji:P0h

(: Il.t.!; "0

f,=-PrM, -V,. rM. -0, ~ e ~pJ,fril1l.'ZJ,.

M ,V" t M. Vt.~c.l"" ttYIi) ttM,'V" t M~VLl

(~, ~il1t.) -'" 1)1

13) A 100 kg football linebacker moving at 2 mls tackles head-on an 80 kg halfback running 3 m/s.Neglecting the effects due to digging in of cleats I" '" Ito

A) this is a simple example of an elastic collision. ' I'jB) the linebacker will drive the halfback backward. l\\.~= ~D''''J

ittmrplayer witrdfive-U1 kward. -0 c z.lA(0) the halfback will drive the linebacker backwar . I --.sJi,

IW/t tv"f. \"7 + 1J.r)IW -!;, '11. l.h. - '{Answer: 0 !)I,l ~J it' , l 1)-Oiff:2 (I 80 lab) - 0,2. 2 ( - V,f

..Y 10<1)a/ I' ' '<.. _14) Car A (mass = 1OOOkg)moves to the right along a level, straig t r a a speed of 6.0 m/s. Itcollides directly with car B (mass = 200 kg) in a completely inelastic collision. What is the momentumafter the collision if car B was initially at rest? 1"\ ~ 7) r M, "V, I ':- V\\ I-V I~ t rY\ •. v..~

A) 2.0 kk mls to the r! ht M,:;' I~ool(j I " I.<:!' .0 kkg mls to the n iV\<~0, f'\.1),,:, M"V'lc -::It''', ~y}1" \VIC). g m s 0 e left:J J_-----.,0) 10. kkg mls to the right 1/'l ; 6.0~& [lroOlt )(' ~dr f(m.Y.O~6}-1.£ 000 ~ ••J JE) zero "Vu.=- cYY.s j ~ I!:'-:J tD _ j t.J ~

~ iAnswer: B Oiff: 2 -r I ?vI: ,

15) Car A (mass = 1000kg) moves to the right along a level, straight road at a speed of 6.0 m/s. Itcollides directly with car B (mass = 200 kg) in a completely inelastic collision. What is the speed of thecar immediately after the collision?

A) 4.0 m/s ""-. ~IOOOk 1\\.,1J"t 1\.\,Vl( ~ frllV,f r tI\,1!J2rB) 6.0 m/s M. - 2 '~ (,•.C zero ~- oqj~ M,:1J" t m7 Vc" :: 1(1". tt11 •.) Vf) 5.0 m 1)1 =- I Ill. "\t). t M .•,. ~ 1)(

O I ' \:) 'I Ie '- v". ms J -----\)}' =-O"k I\'..,r~•.A~swer: D 1) ~") IOoo~ ••~ +1ZOO1'])J"'It) ~~.Dlff: 2 l( ~~' 1 ..t: () "It:

-V1,~lJ?1 12lX1~ • '...117) When a cannon fires a cannonball, the cannon will recoil backward because he

A) momentum of the cannon is greater than the energy of the cannonball.B) momentum of the cannonball and cannon is conserved.C) momentum of the cannon is conserved.D) energy of the cannonball and cannon is conserved.E) energy of the cannon is greater than the energy of the cannonball.

~ --Answer: B P (:: f f P CUI\ D•.••t "'1111 0;1 ball"~dDiff: 2 to L .JcreuM"" f PC(II •..•01'1 1Ja/~ ~ ()18) A mine railroad car, of mass 200 kg, rolls with negligible friction o~ a horizontal track with a speedof 10.0m/s. A 70.kg stunt man drops straight down a distance of 4.0 m, and lands in the car. How fastwill the car be moving after this happens? E?1

r\\,~~, Pi.~ff 7.41.01-A~swer: 7.41 m/s 1"<\ ••.• = 2.~~ _ .Dlff 2 -V!l J\A 1>,. - VV\ z..1.>c.L

I~=- 10"'& "',. I

The Conservation of Linear Momentum (WO~)1D'1tL := 7J22..7 0 Ic'l

2) Jennifer hits a stationary 200. gram ball and it leaves tl1e racket at 40.m/s. If time lapsephotography shows that the ball was in contact with the racket for 40.ms:

(a) What average force was exerted on the racket? F t(b) What is the ratio of this force to the weight of the ball? ',4:: 4- f

Answer: (a)0.20kN M,= ~,"U015 At; 'fO!/o-'.t f:: ~". M"VCJ't1V,'(b) 1.0 x 102 1),~~OM6 ~ ,A.tDiff:2 -V s UD~/ ::>&,UJDrikIONQ} -b~Q..ill

II I I.J '10XI{)-33) Suppose a bug splatters upon your windshield as you drive down the r ad. Wfilc!i ~us1ains the)greater change of momentum? f. t!

A) insufficient information L""; 200 tJ ]B) the bug -C) both the same 4 p := 0 ~r c.los~ 'S,JIJir4 200 IV vBD) the car •• ~ - 100

f.j~t~M {!,lc4;J9.b ~1.Answer: CDiff: 2 L\Pt~= - 4. ~ car

Answer: BDiff 1

4) An 80. gram bullet is fired horizontally into a 1.50 kg block resting on a very slippery tabletop.Before imbedding in the block, the bullet was moving at 210.m/s.

(a) what is the speed of the block immediately after the collision?M,"'" 0,0801:;; I)f:;? M,V,i rlr1tV2,= JII1.,V,f t/l1t Vel

Answer: (a) 10.6 mlsIV\•. " 1.!Zl k~ -V'" (). f1o\, "VI' r- M .:v z ~ = -VI

D'lff3 --V 'f ~I -----Ii.. -:. 2 \0 f\~ M.. t->11.•.

5) Automobile air bags red;:;Ye"~hc~(dtring a collision? &06q"r,){~w/t.) -+-/l,smJfJ"Irj] /6 ~~f theautomobile I, SBk. .= . 6 't<I.llilliUQ_~~forr~ce_ crupon the passenger :7 :JC) the kinetic energy transferred to the passengerD) the impulse exerted upon the passenger F.A-t = 4 r

t~<:.~/-.c.....J~+h~-bMe. i\- ~!:-<l.-~ f-o s f-op (L ~ tLv'jc W\() t'v1G",f 11.""J~e... t="0((. -e ~ I'e.J.U((:.j

6) A 0.17 kg baseball is thrown with a speed of 38.m/s and it is hit straight back to the pitcher with aspeed of 62.m/s. What is the magnitude of the IMPULSE exerted upon the ball by the bat?

v,,:=D.t7~ IMpU./\e..: 4p ~ Pf - fe ~ fr1VI -tl1v,.A~swer: 17. N.s 1), = 31j''1{ l

Dlff:2 1J( ~b2~! ~f,171(~'f..bL"0J- ff2.t7~3'O,.tJJf /7N~ 77) Two equal mass balls (one blue and the other gold) are dropped from the same height, and {rebound off the floor. The blue ball rebounds to a higherj?osition. Which ball is subjected to thegreater magnitude impulse dUring Its collision with the floor? !

A) the gold ball rrljltn..J.C ~ 4PB) Both balls were subjected to the same magnitude impulse.CIt's' ssible to tell since the time intervals and forces are unknown.D) the blue ball

Answer: DDiff: 2

IJ f9JJ 1?J Y\' J

'3 r:::f_L_4t.V_l)~---','Answer: C

Diff: 2

8) A small car meshes with a large truck in a head-on collision. Which of the following statementsconcerning the magnitude of the average collision force is correct?

A) It is impossible to tell since the masses and velocities are not given.B)-rhe.small-caLe2SQeriences the gregteLID'-EUagafm:cGl The small car and the truck experience the same averageD) The truck experiences the greater average orc .

12) An arrow of mass 20. g is shot horizontally into a bale of hay. striking the hay with a constantvelocity of 60. m/s. It penetrates a depth of 20. cm before stopping. What is the average stopping

force acting on the arrow? A-V( =tbOM& F-6t-= 4p t.;().a~7..5 , ,An.swer: 180.N X:: 0.20"" 1)' '"1, A :-. ~ __~=-'()_,'~_'J;_~_J:...••.g_'d.l....•It~--,,~

t v" """'"? \ :: c:rWT4 1.Dlff: 2 M =- 0,0265 '2 V"1I1( -t t 0, ()()67~

\\\vY~c~ 1) = Or1~ tr-o~,- t G/'2 :~o~)2 6}8(}?J).) '/ '"V1'Z{ l%' "',1 .,iJ

Answer: BDiff: 2

14) A machine gun, of mass 35. kg, fires 50. gram bullets, with a muzzle velocity of 750. mIs, at therate of 300. rounds per minute. What is the average fO~ exerted on the machine ~n mount?

Answer: 188.N M:::~,O~ ~')L:?;a;n;wJ5) I {-}J: "'"LV~Diff: 2 lJ : 7s.0f'& / F?:- J:V. :-[p,Ofl.)k1 '(}(X)r~ ••.::.i.7fZ' M,{j)-fiJ)

At": ~05 lrt ?'Os @15) A 2000. kg car, traveling to the right at 30. mIs, collides with a brick wall ana comes to rest i = Ie&1J0.20 s. The average force the car exerts on the wall is

A) 60. MN. y"\'" U'OOV~ f,~t= 1-4fB) 0.30 MN. Ie.. C;C)O.60MN. Vi::: ?>";\6 1:::'_/J,D _~(JO(){ •.••V.301.\17J4;JoO~'\/01);'lD) 12. M N. - ...::::-:i--... =-...JL--L_._.tl:..-.\ __ -::Jfi.__ ...:JJ;.-E) 30. MN. -Uf -=-01; CI t.. O,2-cJ.J

4t -::O,ZO.. L; 3 00,000 rV T,

17) Some automobiles have air bags installed on their dashboards as a safety measure. The impactof a collision causes the bag to inflate, and it then cushions a passenger's head when he is thrownforward in the car. Suppose that such a bag could lengthen the collision time between one's head andthe dashboard by a factor of 10. What effect would this have on the force exerted on the head?

A) The force would be reduced by a factor of about 3.B) The force would be reduced by a factor of about 1000.C) The force would be reduced by a factor of about 10.D) The force would not be reduced, but the energy transferred to the head would be, thereby

minimizing the damage done.E) The force would be reduced by a factor of about 100.

Answer: C ~ A-L ~ A. p'" f ~4P i P L\t ~10XDiff:2 I I ~t f~ lOx tfeeJe/.jl-J,..,f~c.~ct~{1uFrom the graph, determine the change in momentum after 10 seconds of a 100.kg object. -Ht~SClM'(..

F

Answer: DDiff: 2

t FAt ~b,f

F ~N'iSs3t [J(-I{)l1t6,~-/ -7{tJ

21) A 2.0 kg softball is pitched to you at 20. m/s. You hit the ball back along the same path, and at thesame speed. If the bat was in contact with the ball for 0.10 s, the average force the bat exerted was

A)OAOkN. Vi.=ZOd// F=? F;;,t=4PB) 40. N. '''f~ @. ff ~ze -V( ..-W~ -_ 4-(' 2..ot,.\(-20>lA1_:'::,(;lI'9)~~1

0) 0.80 kN. r- __~ "j.J /OJ ~O. ('v\.-2{JLj L\.t ~ O,ios

Answer: 0 4..i~o.I6~ [~ Gc>of'J.)Oiff: 2 _ ~

Elastic and Inelastic Collisions

3) In space, a 4.0 kg metal ball moving 30.m/s has a head-on collision with a stationary similarsecond ball. After the elastic collision, what are the velocities of the balls?

Answer: They exchange velocities: the first beCOmeS{!o, and the second acquires 30. mls in thedirection the first was moving. ~"W\#W\h/01 ,\1 \ h b'll, J ba{l.Oiff2 \." \ 1 ........~ OM ~ \) ~~'€.o - l It o..v U

Y\\h~ l\.e.a bl"\. - p&kJ.ly e\l.Ld--"" (oll1J.I~= pl\e- St-nps ~ o'f{6) A 2200. kg auto moving at 12.0 mls runs into a 3800. kg truck which is moving in the same . -t-direction at 5.00 m/s. The collision is perfectly inelastic. ~ wd-~

(a) What is the speed of the auto immediately after the collision? ~ .5<VI'1e.fY\,::-z.'Z.-O~ 1)l;:~,()/Il!J pi;pr ~iI'\".I'h.l'l.:1

Answer: (a) 7.57 mls .••.1 •• I •. ~I 1'1 ""'"V'l r""O'ff3 f't\. ~ 3t:-OOfte, V1t. V~I "",11" of ,",11,(- tl1. V,/7'Il1. Vrr ( ,Vz;I 1. ~ ~I "",1"/>1 J - ",.,1)1~~ 12-~/ ,"",v" ,MeV •.. =(M,T"'l.)-V1 t • V,.

7) A "" hit' BOoth" BOdthe two bdmpe" look togethee d"'og the oolli,;oo. I, !hi, BO1~inelastic collision? L J!.W J: ::l

A) elastic 1 2. ~ tL.:dJdJ!7J,!J,inelastic DO()

Insu IClent information (it could be either) ~. 1,5'1 t~~~er:B 1S~ huve.. SoaMe.. \J e,to <.lj, ~r~e((c)/ Its/v"", .

8) In an inelastic collision. the final total momentum isA) more than the initial momentum.B~ss.Jhan..lhe-initia m.

<Cl the same as the initial momentum.0) insu IClent information 0

Answer: COiff 1

colll ~l&\<;.Q("~l'r\.j Or\.

-Answer: TRUEOiff2

14) Momentum is conserved during a completely inelastic collision.

W (~ I\- 0 ex.f el'YlJI.- ( {d;,,( e.1

15) In a game of pool, the white cue ball hits the #5 ball and stops, while the #5 ball moves away withthe same . as the cue ball had originally. The type of collision is

elastic.IC or inelastic, depending on the mass of the balls.

C) completely inelastic.D) inelastic.

Answer: ADiff: 2

Jet Propulsion and Rockets

1) Why does ion propulsion, which expels material much faster than ordinary chemical rockets, holdsuch promise for future space travel?

Answer: Much less fuel is needed since the same impulse can be delivered to the rocket by lessmass expelled at greater speed. 'T\c... ~r /' ~ b ~ I' / I IDiff:3 r, Lt" L-l1. c- PfJ led' oUEV' <1 {O~€L/ jJe/l'L'o"1Or {tMe2) In space there is nothing for the rocket to "push against" so how does it accelerate?

Answer: In terms of forces, the rocket pushes the exhaust gases back and they in turn (action-reaction) push the rocket forward. In terms of momentum, in order to conserve momentum since theexhaust gases acquire negative momentum (moving backwards) the rocket acquires positivemomentum (increasing velocity forward).Diff: 3

3) Astronaut Jennifer's lifeline to her spaceship comes loose and she finds herself stranded, "floating"1OO,mfrom the mothership. She throws her 2,00 kg wrench at 20.0 m/s in a direction away from theship. If she and her spacesuit have a combined mass of 200. kg how long does it take her to coastback to her spaceship? ~ I ~ 2.00k"1 LJ

2::. - 2Gy'lI

A) 1000. s Ap: 0 X""/~,,\ M~:;.2.,Oh it _? If8) 750. s "::J t-I - I

~tes [\\, Vll +VY\z 1J2.l :::N\l Vlf T M. .•()ttOO.s

Answer: EDiff: 2 0- MlLJ,f t JY\'2-V2f

VIP -:::-M •.lJz.t :0-M,

rV::::zt

1:. :..z... :; 10011\lJ -0, l'YJ

/

- (jj.. ,01:'j'j-20 'Y,51'2$0,5

•

Difficult

16) A 60. kg person walks along a 100. kg log at the rate of 0.8 m/s (with respect to the log). Withwhat speed does the log move, with respect to the shore?

Answer: 0.3 m/sOiff:2

9) A toy rocket, of mass 60 g, achieves a velocity of 80 m/s after 3.0 s when fired straight up. Whataverage thrust force does the rocket engine exert?

A) 3.4 NB) 1.2 NC) 2.2 N0) 3.3 NE) 1.6 N

Answer: COiff: 2

1) A 60. gram toy rocket achieves a speed of 80. m/s after 3.0 s, when fired straight up. What is theaverage total force on the rocket during the 3 s?

A) 3.4 NB) 1.6 NC) 2.2 N0) 3.2 NE) 1.2 N

Answer: BOiff: 2