For each of the questions, there are four possible

choices. Choose the one you consider correct and

record your choice

d Abox of mass 2 kg is being pushed horizontally

on a smooth surface by a l0 N force. What is

the acceleration of the box?

10N

A Oms2

the friction between the box and the rough

surface?

A 5N B 8NclON Dl2N ( )

6. Abox of mass 4 kg is being pushed horizontally

on a rough surface by a 12 N force. Given thatthe box moved at constant speed of 2 m s-r, what

is the friction between the box and the rough

surface?

()

()

Ms

w,

V'

d

d

Mg

2. A box of mass 2 kg is being pushedhorizontally on a smooth surface by a force

F. Given that the acceleration of the box is3 m s-2, what is the magnitude of force F?

A O.7N B I.5Nc s.ON D 6.0N ( )

3. A box is being pushed horizontally on a

smooth surface by a l0 N force. Given that the

acceleration is 4 m s-2. what is the mass of the

box?

Abox of mass 2 kg is being pushed horizontally

on a rough surface by a l0 N force. Given

that the frictional force is 4 N and there is an

opposing force of 2 N acting against the l0 Nforce as shown, what is the acceleration of the

box?

10N 2N

B 0.2 m s-2

D 20ms-2

B 2.5 kgD 40kg

A 4NC 16NC 5ms2

A 0.4 kg

C 14kg

)

)

()

A 2ms-2C 6ms2

B 12ND 2ON

Frictionalforce=4N

B 4ms2D l2ms2

Frictionalforce=4N

B I ms-2

D 4ms-2

4. Abox of mass 2 kg is being pushed horizontallyon a rough surface by a l0 N force. Giventhat the frictional force is 4 N, what is the

acceleration of the box?

A 3ms-2 B 7ms2C l2ms-2 D 28ms2 ( )

5. Abox of mass 2 kg is being pushed horizontallyon a rough surface by a 10 N force. Given that

the acceleration of the box is I m s 2, what is

8. Abox of mass 2 kg is being pushed horizontallyon a rough surface by a l0 N force. Giventhat the frictional force is 4 N and there is an

opposing force of6 N acting against the l0 Nforce as shown, what is the acceleration of the

box?

0

2

m

m

AC

S'S'

\\,g

t7 Unit 3 Dynamics

Theme 2

Mechanics

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w,9 . A box of mass 2 kg is being pushed horizontallyon a rough surface by a 10 N force. Giventhat the frictional force is 4 N and there is an

opposing force of 14 N acting against the l0 Nforce as shown, what is the acceleration of the

box?

l0N

0

2

AC

mm

s-2

s-2

Frictionalforce=4N

B I ms-2

D 4ms-2 ()

v

tVs

U

10. A box of mass 2 kg travels at 3 m s-rconstant

speed when it is being pushed horizontallyon a rough surface by a 4 N force. What isthe acceleration of the box when the force is

increased to 6 N?

A 0ms-2 B lms2C 2ms-2 D 4ms-2 ( )

11. A box is being pushed across a horizontalground at constant speed. Ifthe push is stopped,

the box will

A stop immediately.B continue to move at constant speed.

C start slowing down.

D move at constant speed for a while and then

slow down. ( )

12. A box is being pushed horizontally along a

rough surface and a constant acceleration is

achieved. If the push is stopped, the box will

A slow down and finally stop.

B continue to move at constant speed.

C accelerate at a lower rate.

D stop immediately. ( )

13. A particle at rest is being pushed by a forcefrom the left and an equal force acted from the

right at the same time. What will happen to the

particle?

d

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A continue to be at rest

B moves either to the right or to the leftC moves either to the top or to the bottomD rotates in circle (

1 4. A pafticle at rest is being pushed by a force fromthe left. An equal force pushed the particle fromthe right after some time. What will happen tothe panicle?

A continue to be at rest

B moves to the right at constant speed

C moves to the left at constant speed

D rotates in circle ( )

15. A particle moving at a constant speed of5 m s-r is being acted on by two l0 N forces as

shown. The particle will

5ms

---|>l0N o 10N<--A stop immediately.B continue to move at 5 m s-r.

C slow down and gradually stop.

D increase its speed gradually.

16. A particle moving at a constant speed of5 m s-r is being acted on by a l0 N force and a8 N force as shown. The particle will

smsl

8N------------___> o l0N

A stop immediately.B continue to move at 5 m s-r,

C slow down gradually.

D increase its speed gradually

17. A force of 12 N acts on block A of mass 2 kgas shown. Given that the floor is smooth, whatis the acceleration of block A?

12N

()

d

A 0ms2C 6ms2

B 2ms-2D l2ms-2 ()

l8 Unit 3 Dynamics

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A 2NC 8N

Tl

A 15NB 3ONC 2ON

D lON

B 4ND 12N

T2

15N30Nl0N20N

)

()

()

18. A force of 12 N acts on block A and block Bof mass 2 kg and 4 kg respectively as shown.

Given that the floor is smooth, what is the

acceleration of block A?

12N

B

Ds-2

s,2

mm

AC

J

6

m

m

2

4

s-2

s-2

v19. A force of 12 N acts on block A and block Bof mass 2 kg ar,d 4 kg respectively as shown.

Given that the floor is smooth, what is the

tension of the string which is between block Aand block B?

12N

P, Q and R are three identical blocks resting on

a smooth surface. Aforce of 30 N is applied at

one end as shown in the diagram below. What

are the tensions 7,, between blocks P and Q, and

7r, between blocks Q and R, in the strings?

T2

30N

Tl

l. P, Q and R are three identical blocks resting on a

rough surface. Aforce of 45 N is applied at one

end as shown in the diagram below. A frictionforce of 5 N acts in the opposite direction on

each block. What are the tensions I,, between

blocks P and Q, and 7., between blocks Q and

R, in the strings?

<-Friction = 5 N

4kgB

2kgA

P a R

W,

V,,

Tl

A 22.5 NB 15NC 45ND ION

Tl

A IONB IONC 3OND ION

Tl

A 3ONB 15NC 15ND 5N

T2

22.5 N30N45N20N

T2

l0N20N30N30N

()

()

()

22. P,Q and R are three blocks resting on a smooth

surface. A force of 60 N is applied at one end

as shown in the diagram below. Given that the

masses of P , Q and R are I kg,2 kg and 3 kgrespectively, what are the tensions I,, between

blocks P and Q, and T, between blocks Q and

R, in the strings?

lkg 2kg 3kgTl T2

60N

P, Q and R are three blocks resting on a rough

surface. A force of 90 N is applied at one end

as shown in the diagram below. Given that the

masses ofP, Q and R are lkg,2 kg and 3 kgrespectively and the frictional forces with the

floor are l0 N, 20 N and 30 N respectively, what

are the tensions I,, between blocks Pand Q, and

in,, between blocks Q and R, in the strings?

lkg 2ke 3kgTl T2

90N

l0N 20N 30N

T2

30N45N25Nl0N

P o R

P a R

45N

t9 Unit 3 Dynamics

B

4kgA

2kg

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40 kg

10 kg

Vro.

W^

Vru.

A 40 kg mass is initially at rest on a smooth

bench and a l0 kg mass is attached to it as

shown.

smooth pulley

/

What is the speed of the l0 kg mass 2 s afterthe masses start moving? (Take g = 10 m s-2)

A 0ms-r B 4ms-rC l0ms-1 D 20ms-' ( )

A 40 kg mass is initially at rest on a rough bench

and a l0 kg mass is attached to it as shown. Africtional force of 20 N opposes the motion ofthe 40 kg mass.

smooth pulley

/

Friction = 20 N

What is the speed of the l0 kg mass 2 s afterthe masses start moving? (Take g = l0 m s-2)

A Oms-r B 3.2ms-1C 4.0ms-' D 20ms-t ( )

T\vo perpendicular forces act on a particle as

shown. What is the magnitude and direction ofthe resultant force on the particle?

4N

o

,t() kg

10 kg

3N

20 Unit 3 Dynamics

v

V,

B 5N

C 7N

D 7N

27 . Three forces act on a particle as shown. Whatis the approximate magnitude of the resultantforce on the particle?

2N

30'----------------

3N

MagnitudeA 5N

A 3.ONC 7.5N

3N

MagnitudeA 5.2NB 5.2NC 7.5ND 7.5N

Direction36.9" clockwise from 4Nforce36.9o anti-clockwise from4N force36.9o clockwise from 4Nforce36.9" anti-clockwise from4N force

()

B 5.2ND 9.ON

,,.l

Jo

4

(

28. Three forces act on a particle as shown. Whatis the approximate magnitude and direction ofa force to balance the three forces?

4N

2Nt---I

I

I30'

oDirection14.3"

345.7"14.3"

345.70 (

I

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V,,

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Cinderella and her stepsisters are snatchinga rigid bangle. The pulling forces of her twosisters are 80o apart with forces of 100 N and

200 N as shown in the figure below.

Iz' Cinderella

too N .-

80' \200 N

What is the smallest force that Cinderella must

exert in order to prevent the bangle from beingpulled towards her stepsisters?

A I2ON B I5ONc 240N D 300N ( )

A pendulum bob of2 kg mass is pulledhorizontally to theright by a 30 N forceas shown. What willbe the approximatefinal tension in the

string when the bob

is in equilibrium?

A 3ON

C 4ON

tension

N

weight

1. Apendulum bob of mass z is pulled horizontally

to the right by a 30 N force as shown. Find ru

given that the tension in the string is 50 N when

the bob is in equilibrium. (Take I = l0 m s-2)

50N

30N

m8

A 2kg B 4kg

B 36ND 45N )

()C 6kg D Skg

2t Unit 3 Dynamics

U 32. A string is used to hang a photo frame of mass

l0 kg on two nails as shown. What is the tension

in the string? (Take g = 10 N kg-')

string

Vrr. *.n of the following shows the correct vector

diagram of an object in equilibrium?

AB

A 33.3 NC lOON

B 5OND 2OON )

()

)

DC

Vro.

R

Which of the following diagrams shows

correctly that force R is the resultant force?

A B

R

DC

R

nails

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35. A lift is held stationary by a cable. Given rhatthe lift has a mass of 500 kg, what is the tensionin the cable? (Take g = l0 N kgi)A ON B 5ONc s00N D s000N ( )

36. Alift is moving downwards at a constant speed

of 2 m s-1. Given that the lift has a mass of500 kg, what is the tension in the cable? (Takeg=10Nkg-t)

A 1000N B 2500Nc 4000N D 5000N ( )

37. A lift is moving upwards at a constant speed of4 m s-1. Given that the lift has a mass of 500 kg,what is the tension in the cable? (Take g =l0 N kg-')

A ON B 5ONc s00N D s000N ( )

38. A lift is moving downwards at a constantacceleration of 2 m s-2. Given that the lift has a

mass of 500 kg, what is the tension in the cable?(Takeg=10Nkg-1)

A 2500N B 4000Nc 5000N D 6000N ( )

39. A lift is moving downwards at a constantdeceleration of 2 m s 2. Given that the lift has a

mass of 500 kg, what is the tension in the cable?(Takeg=l0Nkg-')

A 2500N B 4000Nc s000N D 6000N ( )

A lift is moving upwards at a constantacceleration of 2 m s-2. Given that the lift has a

mass of 500 kg, what is the tension in the cable?

(Takeg=10Nkgi)

A 2500N B 4000Nc 5000N D 6000N ( )

N1iu+t. e lift is moving upwards at a constant

deceleration of 2 m s-2. Given that the lift has a

mass of 500 kg, what is the tension in the cable?(Takeg=l0Nkg-')

A 2500N B 4000Nc s000N D 6000N ( )

Extension Questions

U 42. Abox of mass I kg moves with an acceleration

of 2 m s-2 when a force F is applied on it as

shown. If the frictional force between the boxand the floor is 3 N, calculate the magnitude ofthe force.

a=lms--------------*

F

A ONC 2N

B lND 5N (

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\\,CI

43. An Eskimo is pulling a sledge across level snow.

The sledge has a mass of 15 kg. The Eskimopulls with a horizontal force of 90 N and theconstant force of friction is 60 N. What is theacceleration of the sledge?

A 0.0 m s-2 B 2.0 m s-2

C 4.0ms-2 D 6.0ms-2 ( )

44. A submarine is accelerating through the waterat a constant depth. It is being acted by fourforces as shown.

propellingforce

1upthrust

water

weight IY

Which of the following statements is correct?A The upthrust is balanced by the weight.B The resultant force of the four forces is

zeto.

C Gravity has no effect on the submarine.D The water resistance balanced the propelling

force. ( )

+

22 Unit 3 Dynamics

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45. The diagram below shows a system of sixstrings and a weightless beam holding a 2 kgmass. What are the tensions I, and T, in the twostrings shown? (Take g = l0 N kg t)

T1

T2 light beam

Tr

A 5NB 5NC lOND ION

TlA 6.7NB 6.7NC lOND lON

T2

5N10N5N10N

T2

5Nl0N5Nl0N

()

()

46. The diagram below shows a system of 5 strings

and a beam of mass 1 kg holding a 2 kg mass.

What are the tensions 7, and T, in the twostrings shown? (Take g = 10 N kg-')

ceiling

T1

T2Mass of beam is I kg.

v 47 . The diagram below shows a smooth pulley withtwo masses of 17 kg and Y kg hanging at each

side. Given th atW > V , what is the acceleration

of the system? (Let the acceleration due togravity be g.)

wke vke

A

C

(w -v)sW+V

(w -v)s(W +V)e

(W +V)sW

B

Dg ()

23 Unit 3 Dynamics

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