Modul Intensif Fizik Chapter 2

8/18/2019 Modul Intensif Fizik Chapter 2

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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

Prepared & edited by:

Syaza Izzaty Ismail


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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%.


Syaza Izzaty Ismail


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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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19 Prepared & edited by:Syaza Izzaty Ismail


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2.6 ANAL)SIN# IMP,LSE AND IMP,LSI!E FORCE


• 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.


Syaza Izzaty Ismail


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2.9 :EIN# A;ARE OF THE NEED FOR SAFET) FEAT,RES IN !EHICLES


• 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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• 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.


Syaza Izzaty Ismail


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26 Prepared & edited by:Syaza Izzaty Ismail


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2.? ANAL)SIN# FORCES IN E@,ILI:RI,M


• 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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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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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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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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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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• "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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• 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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!$#*"#, (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%.

Documents

Modul Intensif Fizik Chapter 2