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CHAPTER 2
FORCE AND MOTION
2.1 Linear Motion
A student is able to :2.1.1 Define distance and displacement2.1.2 Define speed and velocity and state that v = s/t2.1.3 Define acceleration and deceleration and state that a = v - u
t2.1.4 alculate speed and velocity2.1.! alculate acceleration / deceleration2.1." #olve problems on linear motion $ith uniform acceleration usin% &i' v = u ( at
&ii' s = ut ( ) at2
&iii' v2 = u2 ( 2as
Distance and Displacement
A: *ill in the blan+ $ith the correct ans$er
1. ,hysical uantities can be divided into 2 :
&a' uantity
&b' uantity
2. Distance is uantity $hich has . and no
3. is a vector uantity $hich has ma%nitude and direction4. 0he # unit for both physical uantities is ..
: omplete the table belo$ :
Aspect Distance Displacement
DefinitionDistance ta+en $ith
consideration of direction
0ype of uantity #calar uantity
# unit
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#peed and elocity
: omplete the table belo$
Aspect Spee !elocit"
Definition ate of chan%e of displacement0ype of physicaluantity
#calar
*ormula#peed
= 0otal distance 0ime
elocity=
# unit m s-1
#ymbol
u, v u denotes initial speedv denotes final speed Avera%e speed = 0otal distance 0ime
u, v
u denotes initial velocityv denotes final velocity5e usually consider the for$ardmotion & to the ri%ht ' as positiveand the bac+$ard & to the left'as ne%ative '
Acceleration
D: *ill in the blan+ $ith the correct ans$er.
1. Acceleration is the rate of chan%e of ............
2. Acceleration 6 a = *inal velocity - nitial velocity0ime ta+en
3. 0he # unit of acceleration is ....
4. Acceleration is a ...... uantity
!. Acceleration occurs $hen an ob7ect moves $ith . velocity.
". Deceleration occurs $hen an ob7ect moves $ith velocity.
8: #olve the problem.
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a =
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1. A car starts from points from point 9 and moves to 6 !; m to the north in "; s. 0he car then
moves to 6 12; m to the $est in 4; s. *inally6 it stops.
alculate the :
&a' total distance moved by the car
&b' displacement of the car
&c' speed of the car $hen it is moves to the north
&d' velocity of the car
&e' avera%e speed of the car
2. A bus stops at a station to pic+ passen%ers up. t then moves and attains a velocity of 1! m s-1 in < s. 5hat is the acceleration of the bus
*. omplete the table belo$ $ith the correct ans$er
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ncreasin% short increasin% far same
#peed decreasin% lo$ hi%h decreasin%
,attern 8>planation
&a' Direction of motion
nitial *inal
0he distance bet$een the dots is the . t sho$s that theob7ect is movin% $ith
&b' Direction of motion
nitial *inal
0he distance bet$een the dots is .. t sho$s that theob7ect is movin% very .
&c' Direction of motion
nitial *inal
0he distance bet$een the dots is . t sho$s that thespeed of the ob7ect is movin% $ith .
&d' Direction of motion
nitial *inal
0he distance bet$een the dots is . t sho$s that thespeed of the ob7ect is .
&e' Direction of motion
nitial *inal
0he distance bet$een the dots is . t sho$s that thespeed of the ob7ect is
#$ Determine t%e acceleration o& a trolle" &rom t%e tic'er tape
1. 0he tic+er tape is divided into ! parts. 8very part has 2 tic+s as sho$n in fi%ure belo$.
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. . . . . . .
. . . . . . .
. . . . . . .
. . . . . .
. . . . . . . . . . . . . . . .
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*ind the acceleration.
1 cm ! cm
A D 8 *
#olution :
Step Sol(tion
1. 0ime ta+en of one part 9ne part = . 0ic+s = . > ;.;2 s = . #
2. initial velocity6 u = s initial t initial
u = cm s
= . cm s-1
3. *inal velocity6 v = s finalt final
v = cm s
= . cm s-1
4. Determine the total time
0otal time = & 0otal parts ? 1' > time of one part
0otal time6 t = & ' > .. s
= > ... s
= . #
!. Acceleration6 a = v – u t
a = v – u t
== cm s-2
0he euations of motion:1. omplete the table belo$
,hysical uantity #ymbol
Displacement
v
nitial velocity
acceleration2. @ist the euations of linear motion.
&i'
&ii'
&iii'
&iv'
uestions
1. #olve the follo$in% problems usin% the euations of linear motion&a' A car moves from rest to a velocity of 1; ms-1 in ! s .alculate the acceleration of the car
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&b' A car travelin% $ith a velocity of 1; m s-1 accelerates uniformly at a rate of 3 m s-2 for 2; s.
alculate the displacement of the car.
&c' A van that is travelin% $ith velocity 1" m s-1 decelerates until it comes to a stop. f the
distance traveled is < m6 calculate the deceleration of the van.
2.2 ANAL)SIN# MOTION #RAPH
A student is able to :2.2.1 ,lot and interpret displacement-time and velocity-time %raphs
2.2.2 Deduce from the shape of a displacement-time %raph $hen a body is:i' at restii' movin% $ith uniform velocity
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iii' movin% $ith non-uniform velocity2.2.3 Determine distance6 displacement and velocity from a displacement-time %raph2.2.4 Deduce from the shape of a velocity-time %raph $hen a body is:
i' at restii' movin% $ith uniform velocityiii' movin% $ith uniform acceleration
2.2.! Determine distance6 displacement and velocity and acceleration from a velocity-time %raph2.2." #olve problems on linear motion $ith uniform acceleration
A: Describe the motion of an ob7ect as sho$n in the follo$in% motion %raphs.
&a' 0he Displacement-0ime raph
raph of s a%ainst t 8>planation
s/m
; t/s
0he displacement of the ob7ect from a fi>ed point is
.. 0herefore6 the velocity of the
ob7ect is .
s/m
; t/s
0he %radient of the %raph = ..of the ob7ect.
0he %radient of the %raph is .6 therefore thevelocity of the ob7ect is .
s/m
; t/s
0he %radient of the %raph .. $ith time.
0herefore the velocity of the ob7ect . $ith
.
&b' 0he velocity ? time %raph
raph of v a%ainst t 8>planation
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v/m s-1
t/s
elocity of ob7ect is . . 0he ob7ect is
v/m s-1
t/s
0he ob7ect is movin% $ith uniform
v/m s-1
t/s
0he %radient of the %raph =
0he %radient of the %raph is
0herefore6 the acceleration of the ob7ect is
v/m s-1
t/s
Area under the %raph = .
. Describe the motion of a runner $ho is runnin% in a strai%ht line
s/m
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20
25
15
10
5
C
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v/m s-1
t/s
D
A ! 1; 1! 2; 2!
O t*s ! 1; 12 1!
#olution :
Botion of the runner
9 - A unnin% $ith a uniform velocity of 3 m s-1
A-
-
- D
: #tudy the velocity-time %raph.
alculate:&i' the acceleration6 a, for sections A6 and D
&ii' total displacement
2.+ ,NDERSTANDIN# INERTIA
A student is able to :2.3.1 8>plain $hat inertia is2.3.2 elate mass to inertia2.3.3 ive e>amples to reduce the ne%ative effects of inertia
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A B
D
10
5
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A. *ill in the blan+s or underline the correct ans$ers
1.
5hen the bus stops suddenly our feet are brou%ht to rest but due to inertia6 our body
tends to continue its &for$ard/bac+$ard' motion. 0his causes our body to 7er+
CCCCCCCCCCCCCCCCCCC.&thro$n for$ard'
2.
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5hen the bus moves suddenly from rest our feet are carried &for$ard/bac+$ard' but
Due to inertia our body tends to +eep us &rest/movin%' . 0his causes our body to
fall CCCCCCCCCCCCCCCCCC. &thro$n bac+$ards'
3. 0he inertia of an ob7ect is the.................................. of the ob7ect to remain at ...........
or if ...................... to continue its uniform motion in a strai%ht line
4. 0he mass of an ob7ect is the amount or uantity of matter contained in the ob7ect.
!. 0he # unit of mass is ..
". 0he mass of an ob7ect is .... $herever it is measured. t is different from
......... $hich is affected by the ...... of %ravity.
. An ob7ect $ith a lar%er mass has a ............ nertia.
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E&&ects o& inertia
. 8>plain the positi-e effect by usin% the clues %iven.
.Batch the correct e>planation to each of the characteristics
haracteristic 8>planation
&a' 0he tan+ $hich carries liuid in alorry should be divided into smaller
tan+s
Eold the passen%ers to their seatdurin% collision
&b' the part bet$een the driverFs seat andload should have stron% steel structure
,revent the driver from hittin% thesteerin% in an accident
&c' #afety belts ,revent the load from bein% thro$n tothe front
&d' Airba% 0o reduce the effects of inertia $henstopped suddenly.
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Positi-e e&&ectO& inertia
lue : ,our our 0omato sauces
lue: unnin% Gi%-Gi% $hen chasedby a bull.
lue : Dryin% a $et umbrella
lue : 0i%hten the Eammer head
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2. ANAL)SN# MOMENT,M
A student is able to :2.4.1 Define the momentum of an ob7ect2.4.2 Define momentum&p' as the product of mass &m' and velocity&v' ie p=mv2.4.3 #tate the principle of conservation of momentum2.4.4 Describe the applications of conservation of momentum2.4.! #olve problems involvin% momentum
A. *ill in the blan+ $ith the correct ans$er
1. Bomentum is defined as the product of ... and .....
2. 0he formula of momentum is %iven by :
Bomentum = ........ > ....
3. Bomentum is a .. uantity
4. 0he # unit of momentum is
!. Bomentum ..... $hen velocity ......
". 0he principle of conservation of momentum states that the total momentum in a
closed ... of ob7ect is .....
. 0he total momentum .. the collision is .. to the total momentum
.. after the collision6 if no .... acts on the system.
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Bomentum :
2. ollision : oth ob7ects move to%ether after collision. . s conserved.
efore collision after collision
Bomentum :
3. 8>plosion : 0$o or more bodies in contact $ill be after the e>plosion
efore e>plosion after e>plosion
Bomentum :
. omplete the table belo$
8lastic collision nelastic collision 8>plosion
&a' oth bodies $ill separateafter collision
0$o or more bodies in contact $illbe separated after the collision
&b' 0he total momentum isconserved
0he total momentum is conserved
&c' 0he total +inetic ener%yis conserved
&c' 0otal ener%y is conserved 0otal ener%y is conserved
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m1m2 m1 + m2
u2 = 0
u1
v
(m1 + m2), u = 0 v1
m2
v2
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. #olve the follo$in% problems
1. ar A of mass 1;; +% travelin% at 3; m s-1 collides $ith ar of mass H; +% travelin% at 2; m s-1 infront of it. ar A and move separately after collision. f ar A moves at 2! m s-1 after collision6determine the velocity of ar after collision.
2 : A trolley of mass 4 +% moves at 3 m s-1 and collide $ith a trolley of mass 2 +% $hich is movin% in the
opposite direction at 1 m s-1. After the collision6 both trolleys move to%ether $ith the same velocity.
5hat is their common velocity
3 : A bullet of mass 2 % is shot from a %un of mass 1 +% $ith a velocity of 1!; m s-1 . alculate
the velocity of the recoil of the %un after firin%.
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2./ ,NDERSTANDIN# THE EFFECTS OF A FORCE
A st(ent is a0le to $
• escri0e t%e e&&ects o& 0alance &orces actin on an o0ect
• escri0e t%e e&&ects o& (n0alance &orces actin on an o0ect
• etermine t%e relations%ip 0et3een &orce4 mass an acceleration i.e F5ma
• Sol-e pro0lems (sin F 5 ma
1. Ans$er the follo$in% uestions.
&a' 5hat are the effects of a force $hen actin% on an ob7ect
A force can.
&i' CCCCCCCCCCCCCCC a stationary ob7ect
&ii' CCCCCCCCCCCCCCC a movin% ob7ect
&iii' chan%e the CCCCCCCCCCCCCCCCCCC of an ob7ect
&iv' chan%e the CCCCCCCCCCCCCCCCCCC of an ob7ect
&b' *orce is a & scalar / vector ' uantity .
&c' 5hat is the # unit for force
0he #.. unit for force is CCCCCCCCCCCC .
2. *ill in the blan+s $ith appropriate ans$ers for balanced and unbalanced forces.
&a' *orces actin% on an ob7ect are said balanced $hen the net force is CCCCCCCCCCCCCCCC.
&b' 5hen the forces actin% on an ob7ect are balanced6 it is either at CCCCCCCCCCCCCCC or movin% $ith
CCCCCCCCCCCCCCCCCC CCCCCCCCCCCCCCCCC.
&c' An ob7ect $ill CCCCCCCCCCCCCCCCCCCCCCCCCCC if the forces actin% on it are not balanced.
3. Dra$ the %raph and state the relationship bet$een acceleration6 a6 force6 F and mass6 m.
&i'
&m is constant' &* is constant'
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a
*
a
m
1
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&ii' elationship :
a is CCCCCCCCCCCCCCCCCCCCCCCCCC to *
elationship :
a is CCCCCCCCCCCCCCCCCCCCCCCC to m
&iii' ombine the relationship:
* = + I + is constant &+ = 1'
* =
&b' 0he relationship bet$een F 6 m and a is +no$n as Je$tonFs CCCCCCCCCCCCCCCCCC la$ of
CCCCCCCCCCCC.
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a ∝
∝*
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4. #olve the follo$in%.
&a' A force6 * is reuired to move an ob7ect of mass 1;;; +% $ith an acceleration of 3 m s-2. alculate* $hen&i' ob7ect is on a smooth surface&ii' ob7ect is on a surface $here the frictional force is 2;; J
&b' A bloc+ of mass 2; +% is pulled alon% the %round by a force6 * of "; J. 0he frictional force is 1; J.alculate the acceleration of the bloc+.
&c' A car of mass 12;; +% $hich is travellin% at H; +m h-1 comes to a stop in a distance of !; m $henthe bra+es are applied. 5hat is the avera%e bra+in% force of the car
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F
a = 3 m s-2
m = 1;;; kg
F
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2.6 ANAL)SIN# IMP,LSE AND IMP,LSI!E FORCE
A st(ent is a0le to $
• E7plain 3%at an imp(lsi-e &orce is
• #i-e e7amples o& sit(ations in-ol-in imp(lsi-e &orces
•
De&ine imp(lse as a c%ane o& moment(m ie Ft 5 m-8m(• De&ine imp(lsi-e &orce as t%e rate o& c%ane o& moment(m in a collision or
e7plosion i.e F 5 m-8m( t
• E7plain t%e e&&ect o& increasin or ecreasin time o& impact on t%e manit(e
o& t%e imp(lsi-e &orce
• Descri0e sit(ations 3%ere an imp(lsi-e &orce nees to 0e re(ce an s(est
3a"s to re(ce it
• Descri0e sit(ations 3%ere an imp(lsi-e &orce is 0ene&icial
• Sol-e pro0lems in-ol-in imp(lsi-e &orces
1. Define impulse and impulsive force by completin% the follo$in% table.
#ituation 8>planation
A ball of mass6 m is +ic+ed
$ith a force6 F. 0he time of
contact is t . 0he ball
accelerates from u to v .
*rom : * = ma* = m
* =
mv ? mu = chan%e of
mpulsive force
*
*
* =
=
mpulsive force is defined as the .........................
. in a collision or
e>plosion.
mpulse
= force > time
mpulse = * t =
= chan%e of .......
# unit for impulse is ..... or ......
2' &i' *ill in the blan+s $ith appropriate ans$ers.
mpulsive force is a ..... force $hich acts over a very ........ time interval
durin% ..... and ....
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t
t
1∝
mumv−∝
t
t
mumv−
∴
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&ii' y usin% the fi%ures %iven6 determine $hether the impulsive force actin% is lar%e or small.
3. 0$o e%%s of
the same mass are released from the same hei%ht6 as sho$n in 0he fi%ure belo$. 8%% A falls on aconcrete floor $hile e%% B falls on a thic+ folded to$el.
sin% *i%ure A and *i%ure6 compare the conditions of thee%%s after the fall and e>plain the
relationship bet$een thematerial $here the e%%s landedand the force actin% on the e%%s
upon landin%.
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*i%ure A *i%ure
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.......................
.......................
......................
......................
4. A tennis ball of mass 4! % travels at a velocity of ; m s ?1 immediately after it is struc+ by a rac+et.
0he time of contact bet$een the tennis ball and the
rac+et is ;.! ms. alculate &a' imp(lse
&b' imp(lsi-e &orce e>erted on the ball.
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2.9 :EIN# A;ARE OF THE NEED FOR SAFET) FEAT,RES IN !EHICLES
A st(ent is a0le to $
• Descri0e t%e importance o& sa&et" &eat(res in -e%icles
Sa&et" &eat(res Importance
,added dashboardTo cushion an impact and increases the ___________ __________
of collision so the _______________ __________ produced isthereby reduced
Eead rest
0o prevent the $indscreen from shatterin%.
Automatic air ba%
#afety seat belt
0o minimiGe the force actin% from a side- on collision.
Anti-loc+ bra+in% system
0o increase the time interval of impact so that the resultantimpulsive force is reduced.
2.< ,NDERSTANDIN# #RA!IT)
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CCCCCCCCCCCCCCC CCCCCCCCC (ABS
Shatter proof CCCCCCCCCCC
Side impact bars
Automatic air CCCC
!ead CCCCCC
"einforced passen#er compartment
rumple $ones
Safety seat CCCCCCCC
%added CCCCCCCCCCC
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A st(ent is a0le to $
• E7plain acceleration (e to ra-it"
• State 3%at a ra-itational &iel is
• De&ine ra-itational &iel strent%
• Determine t%e -al(e o& acceleration (e to ra-it"
• De&ine 3ei%t =;> as t%e pro(ct o& mass =m> an acceleration (e to ra-it"
=> i.e ;5m• Sol-e pro0lems in-ol-in acceleration (e to ra-it"
1. omplete the follo$in% by fill in the appropriate ans$er.
a. An ob7ect $ill ................ to the surface of the earth because it is pulled by
..
b. 0he pull or force of %ravity also +no$n as .....
c. 5hen an ob7ect falls $ithout encounterin% any resistance and under the force of ......... only6
the ob7ect is said to be .
d. All ob7ects... freely $ith the same
acceleration re%ardless of their and
e. 0he constant .. of ob7ects fallin% freely due
to the force of .. is +no$n as
6 %.
f. ,ractically6 a free . can only ta+e place in
. $here there is no air resistance.
%. 0he re%ion around the earth is the ………….....………. field of the earth.
h. 0he %ravitational field stren%th is defined as the &&&&&&. .....&&&& actin% on a 1 +% mass.
i. 5hen an ob7ect fallin% freely6 acceleration due to %ravity6 % = .....
2. #tate the differences bet$een $ei%ht and mass in the table belo$.
5ei%ht Bass
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vacuum
!"#$
%$a!&$'
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1. the %ravitational force act on the ob7ect.
2.
3. vector uantity
4.
!. # unit : Je$ton &J'
1.
2. constant uantity every$here
3.
4. base uantity6 mass = m
!.
#olve the problem belo$
3. A coconut falls from rest and hit the %round after 1.2 s.
&a' 5hat is the velocity of the coconut 7ust before hits the
%round
&b' alculate the hei%ht of the coconut before it fall.
4. A stone is thro$n vertically up$ards $ith a velocity of 2; m s-1. f % = 1; ms-26 calculate
&a' the ma>imum hei%ht reached
&b' the time ta+en for the stone to return to its ori%inal position.
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2.? ANAL)SIN# FORCES IN E@,ILI:RI,M
A st(ent is a0le to $
• Descri0e sit(ations 3%ere &orces are in e(ili0ri(m
• State 3%at a res(ltant &orce is
• A t3o &orces to etermine t%e res(ltant &orce
• Resol-e a &orce into t%e e&&ecti-e component &orces
• Sol-e pro0lems in-ol-in &orces in e(ili0ri(m
1. *ill in the blan+s.
i' *orces that act on an ob7ect are said to be in ...... $hen the ob7ect is
. or is movin% at ....... .
ii' 0he net force that acts on an ob7ect $hen t$o or more forces act on it is +no$n as the
..... ........
iii' 5hen ............... is reached6 the resultant force actin% on the ob7ect is .........iv' Je$tonFs ........... la$ of motion states that to every ............. there is an eual but
opposite ..........
v' A force can be resolved into component $hich are ......... to one another.
EoriGontal cpmponent *> =
ertical component *y =
2. n the table belo$6 mar+ and label all the forces that act on the ob7ect.
i' A bo> is at rest on a table. ii' An ob7ect that is suspended by a rope.
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iii' An airplane flyin% at a constant velocity. iv' A trolley bein% pushed at a constantvelocity
v' A bo> of mass 4 +% is bein% pulled by a force
of "; J at an an%le of 3; ; to the surface of a
floor. alculate
&a' the component of the force $hich causes
the bo> to move for$ard.&b' the acceleration of the bo> if the frictional
force bet$een the floor and the bo> is ! J.
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300
60
4 kg
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vi' A man pushes a bo> of mass 4; +% is up an
inclined plane. 0he inclined plane ma+es an an%le
of 3; ; $ith the horiGontal floor. 0he frictional force
actin% bet$een the inclined plane and the bo> is12; J. f the man pushes the bo> $ith a force of
4;; J6 calculate the acceleration of the bo>.
vii'
A 4 +% trolley is connected by a rope to a load of
mass " +%. 0he friction bet$een the table and the
trolley is 1! J. 0he load is then released.
Assumin% that the pulley is smooth and the rope is
of ne%li%ible mass6 find
&a' the resultant force that act on the system
&b' the acceleration of the system
&c' the tension of the rope
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" +%
4 +%#mooth pulley
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viii' 0$o loads of mass 3 +% and ! +% are connected by a
rope $hich passes throu%h a smooth pulley. f the
system is released from rest6 calculate the acceleration
of the ! +% load.
3 *orces in euilibrium
i A bloc+ of mass " +% is suspended vertically by a
strin% tied at 9 to the strin% A9. f the system is in
euilibrium6 dra$ a vector dia%ram &trian%le of
forces' and hence determine the tension of strin%
9A and 9.
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Syaza Izzaty Ismail
3 +%
! +%
30 0A
B
6 kg
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**)
A lamp of mass 1.! +% is hun% from a beam
as sho$n in the dia%ram. alculate the tension
in the rope.
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1.5 kg
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2.1B ,NDERSTANDIN# ;OR4 ENER#)4 PO;ER AND EFFICIENC)
LEARNIN# O,TCOMES $
A student is able to'
• )plain the process of define *or+ ( as the product of an applied force (F and displacement (s of
an ob-ect in the direction of the applied force ie = Fs
• State that *hen *or+ is done ener#y is transferred from one ob-ect to another
• efine +inetic ener#y and state that + = / mv0
• efine #ravitational potential ener#y and state that p = m#h
• State the principle of conservation of ener#y
• efine po*er and state that %=1t
• )plain *hat efficiency of a device is
• Solve problems involvin# *or+, ener#y, po*er and efficiency
#809J A. hoose the correct $ord in the brac+et.
1. 5or+ is the product of applied force and &distance/displacement' in the directionof the applied force.
2. 5hen the $or+ is done &force /ener%y ' is transferred from one ob7ect to another.
3. 0he $or+ done is eual to the amount of &temperature / ener%y' transferred.
4. 0he # unit for $or+ is &7oule / $att'.
#809J . *ill in the blan+ $ith the correct ans$er.
postion unchan%ed ener%y motion
1. Kinetic ener%y is the ener%y of an ob7ect due to its
2. ravitational potential ener%y is the ener%y of an ob7ect due to its in the %ravitational field
3. 0he principle of conservation of ener%y states that canbe transferred from one form to another but it cannot be created or destroyed.
4. 0he principle of conservation of ener%y e>plains that the total amount of ener%yal$ays remains .
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#809J . #tate or false for each of the follo$in% statements.
1. ,o$er is the rate of doin% $or+
2. 0he efficiency of a device is the percenta%e of the ener%yinput that is transformed into useful ener%y.
#809J D : #tate the transformation of ener%y.
Li%t ener" #ra-itational potential ener"
So(n ener" Elastic potential ener"
#tatement *rom 0o
1. Durian falls to the %round Kinetic ener%y(
sound ener%y
2. A bulb connected to a dry cellli%hts up
8lectrical ener%y heat ener%y(
3. A bell rin%s $hen the s$itch ispressed
8lectrical ener%y
4. 0he motion of an arro$ $hen
an archer releases the strin%
Kinetic ener%y(
sound ener%y
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#809J 8 : Ans$er all uestions.
5or+ done
*orce and displacement in the samedirection
*orce and displacement in difference direction
5 = *.s 5 = 5or+
* =
s = CCCCCCCCCCC
5 = *L . s
5 = CCCCCCCCCC 5 = $or+
* = force
s = displacement
M = an%le bet$een CCCCCC
and CCCCCCCCCCCCC
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Syaza Izzaty Ismail
F
M
FF
F
F F F
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Dia%ram &a'Dia%ram &b'
1. Dia%rams &a' and &b'sho$s a boy pushin%a load and a$ei%htlifter liftin% aload of "; +%
a' alculate the$or+ done
i. by the boy
ii. by the $ei%htlifter in liftin% the load.
2. AGman is pullin% a bo> $ith a force of !; J at an an%le of ";o from the horiGontal.alculate the $or+ done to move the bo> to a distance of 3 m.
3. #amy releasin% 2 +% metal ball from a buildin% of 4; m hei%ht
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Syaza Izzaty Ismail
D*p-ac$m$#! = 3 m
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&0a+e the acceleration due to %ravity is 1; ms -2'
a' At the hei%ht of 4; m6 the metal ball has & %ravitational potential ener%y / +inetic ener%y '
b' Nust before the metal ball hits the %round6 the ma>imum ener%y that it has is & %ravitationalpotential ener%y / +inetic ener%y '.
c' alculate
i' 0he ener%y of the metal ball at the hei%ht of4; m.
ii' the +inetic ener%y of the metal before it hits the %round.
d' 5hat is the principle used in c ii'
!. A motor liftin% a $ei%ht 1 +% to a hei%ht of 4.; m in 4 s. 0he input ener%y supply to the motor inone second is 2; N. alculate
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Syaza Izzaty Ismail
Betal ball
4; meter
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a' po$er of the motor
b' the efficiency of the motor
2.11 APPRECIATIN# THE IMPORTANCE OF MAIMIIN# THE EFFICIENC) OF DE!ICES
LEARNIN# O,TCOMES $
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A student is able to'
• "eco#ni$e the importance of ma)imi$in# efficiency of devices in conservin# resources
A. *ill in the bo> $ith the correct terms.
Kinetic *riction in en%ine esistance in electrolyte
esistance 8lectrical hemical
@i%ht Eeat
De-ice Con-ersion o& ener" Loss o& ener" Loss o& ener"(e to
ulb 8lectrical O Eeat
,etrol en%ine hemical O Eeat and sound
8lectric fan O Kinetic esistance incoil ( bearin%
attery O 8lectrical Eeat
. nderline the correct statement belo$.
Statement Ans3er
1. Bost of the ener%y in mechanical devices loss as heat andsound.
&0rue/*alse'
2. A ma7or cause of inefficiency in machines is due to friction. &0rue/*alse'
3. 0he output ener%y of devices al$ays more then input ener%y. &0rue/*alse'
4. Ba>imiGin% the efficiency of devices ma+es the best use of theinput ener%y and reduces ener%y $asta%e.
&0rue/*alse'
!. Ba>imiGin% the efficiency of devices helps to conserve ener%yresources.
&0rue/*alse'
". 5hen ener%y transformations ta+e place6 not all of ener%y isused to do useful $or+.
&0rue/*alse'
2.12 ,NDERSTANDIN# ELASTICIT)
LEARNIN# O,TCOMES $
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A student is able to'
• efine elasticity
• efine !oo+e2s 3a*
• efine elastic potential ener#y and state that p = / +)0
• etermine the factors that affect elasticity
• escribe applications of elasticity
• Solve problems involvin# elasticity
#809J A : *ill in the blan+s $ith the correct $ord or terms.
e>tension *orce constant $or+ ener%y transferred
8lastic limit elastic potential ener%y ar sprin% support elasticity
A cushion directly proportional #prin% balance
1. 0he property of materials that can return to its ori%inal shape or siGe $hen the e>ternal force no lon%eracts on it is +no$n as CCCCCCCCCCCCCCCCCCCCCCCCCCCC.
2. CCCCCCCCCCCCCCCCCCCCCCCCCC of a sprin% is the ma>imum force that can be applied to a sprin% suchthat the sprin% $ill be able to be restored to its ori%inal len%th $hen the force isremoved.
3. Eoo+eFs @a$ states that the e>tension of a sprin% is CCCCCCCCCCCCCCCCCCCCCCCCCto applied forceprovided that the elastic limit is not e>ceeded.
F 5 ' 7
5here * = *orce on the sprin%
+ = CCCCCCCCCCCCCCCCsprin%
> = CCCCCCCCCCCCCCof the sprin%
4. A sprin% that is stretched or compressed stores CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC.
!. 5hen a force acts on a sprin%6 CC is done. 0he $or+ done is stored as elastic potential ener%y.
". Applications of elasticity
a' CCCCCCCCCCCCCCCCCCCCCCCCCis used to support our body $hen $e sit on it them.
b' CCCCCCCCCCCCCCCCCCCCCCCCC enable passen%ers in a car to feel comfortable
even $hen it travels on a bumpy road.
c' CCCCCCCCCCCCCCCCCCis used to measure mass/$ei%ht $hich is stretched $hen a load is hun% on it.
#809J : *actors that affect the elasticity of a sprin%. omplete the table belo$.
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0he lar%er the smaller
0he shorter elasticity
*actor elationship to elasticity
1. @en%th the sprin%6 the lar%er the force
constant of the sprin%.
2. Diameter of sprin%
&coil'
0he lar%er the diameter of a sprin% &coil'6
the force constant of the sprin%.
3. Diameter of sprin% $ire the diameter of sprin% $ire6 the
lar%er the force constant of the sprin%.
4. 0ype of material 0he CCCCCCCCC of a sprin% depends on the
material it is made of.
#809J : Ans$er all the uestion.
1. 0he force-e>tension %raphs for t$o sprin%s6 and # are sho$n belo$. omplete the table that
follo$s.
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Syaza Izzaty Ismail
!$#*"#, (cm)
F"'c$, F ()
0
20
10
40
/
5
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Statement Sprin R Sprin S
0he %radient of the %raph
0he force constant of sprin%
*orce needed to e>tend 1 cm of the
sprin%
0he area under the %raph $hen the
sprin% is e>tented by ! cm
8 lastic potential ener%y $hen the sprin%
is e>tented by ! cm
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#prin% CCCCCCCCC is more stiff compared to sprin%CCCCCCCCC.
5hen each sprin% is e>tended by ! cm6 sprin% CCCCCCCCCCCCstores more
elastic potential ener%y than sprin% CCCCCCCCCCCCC
2. 0he fi%ures belo$ sho$s the arran%ement of apparatus in an e>periment to determine therelationship bet$een the e>tension6 e of a sprin% 0 $ith $ei%ht6 W . 0he relationship of e and W issho$n in the %raph.
a' ased on the %raph6
i. Bar+ $ith a cross &>' the elastic limit of the sprin%.
ii. Jame the la$ that is related to the %raph before the elastic limit is e>ceeded.
iii. #tate the relationship bet$een W and e before the elastic limit.
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iv. Determine the value of e $hen W = < J. #ho$ on the %raph6 ho$ you determinethe value of e.
b' 0he sprin% stores ener%y $hen it is e>tended.
i' Jame the type of ener%y stored in the sprin%.
ii' alculate the force constant of the sprin% in # unit.
iii' alculate the area under the %raph6 $hen the sprin% is e>tended from ; cm to 4 cm.
iii' alculate the ener%y stored in the sprin% $hen it is e>tended by 4 cm.
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iv' 5hat is the relationship bet$een area under the %raph and the ener%ystores in the sprin%.