Laws Of Motion Test

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Question 1
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A stone of mass 0.25 kg tied to the end of a string is whirled round in a circle of radius 1.5 m with a speed of 40 rev./min in a horizontal plane. The speed is then increased beyond the maximum permissible value, and the string breaks suddenly, which of the following correctly describes the trajectory of the stone after the string breaks.

A
The stone flies off at an angle with the tangent whose magnitude depends on the speed of the particle.

B
The stone moves radially inwards.

C
The stone flies off tangentially from the instant the string breaks.

D
The stone moves radially outwards.

Question 2
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A man of mass 70 kg stands on a weighing scale in a lift which is moving upwards with a uniform speed of 10 m s−1, what would be the reading on the scale?

A
105 kg

B
75 kg

C
70 kg

D
35 kg

Question 3
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Give the magnitude and direction of the net force acting on a stone of mass 0.1 kg lying on the floor of a train which is accelerating with 1 ms⁻², the stone being at rest relative to the train. Neglect air resistance.

A
0.1 N along the direction of motion

B
0.2 opposite to the direction of motion

C
0.1 N opposite to the direction of motion

D
1.0 N in the direction of motion

Question 4
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Newton’s third law states that when two bodies interact.

A
they exert forces on each other that at each instant are equal in magnitude and opposite in direction.

B
they exert forces on each other that at each instant are equal in magnitude and same in direction.

C
they exert forces on each other that at some instants are equal in magnitude and opposite in direction.

D
they exert forces on each other that at some instants are equal in magnitude and same in direction.

Question 5
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Force is required

A
to start a stationary object and to stop a moving object.

B
only to keep an object moving.

C
only to stop a moving object.

D
only to start a stationary object moving.

Question 6
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According to Newton's third law of motion, the action and reaction forces are

A
not equal in magnitude and opposite in direction

B
not equal in magnitude and same in direction

C
equal in magnitude and same in direction

D
equal in magnitude and opposite in direction

Question 7
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According to first law of motion

A
body acted on by no net force moves with increasing velocity and negative acceleration

B
body acted on by no net force moves with constant velocity (which may be zero) and zero acceleration

C
body acted on by net force moves with constant velocity (which may be zero)

D
body acted on by zero net force moves with non zero acceleration

Question 8
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Give the magnitude and direction of the net force acting on a stone of mass 0.1 kg lying on the floor of a train which is accelerating with 1 ms⁻², the stone being at rest relative to the train. Neglect air resistance.

A
1.0 N in the direction of motion

B
0.1 N opposite to the direction of motion

C
0.1 N along the direction of motion

D
0.2 opposite to the direction of motion

Question 9
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A man of mass 70 kg stands on a weighing scale in a lift which is moving upwards with a uniform acceleration of 10 ms⁻² what would be the reading on the scale?

A
150 kg

B
120 kg

C
130 kg

D
140 kg

Question 10
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A helicopter of mass 1000 kg rises with a vertical acceleration of 15 ms⁻². The crew and the passengers weigh 300 kg. Give the magnitude and direction of the force on the floor by the crew and passengers,

A
3000 N upward

B
4500 N upward

C
7500 N upward

D
1500 N upward

Question 11
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A train runs along an unbanked circular track of radius 30 m at a speed of 54 km/h. The mass of the train is 106 kg. What is the angle of banking required to prevent wearing out of the rail?

A
27^∘

B
37^∘

C
42^∘

D
32^∘

Question 12
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According to second law of motion

A
The momentum of a body is directly proportional to the applied force and takes place in the direction in which the force acts

B
The change of momentum of a body is directly proportional to the applied force and takes place in the direction in which the force acts

C
The rate of change of momentum of a body is directly proportional to the applied force and takes place in the direction in which the force acts

D
The momentum of a body is directly proportional to the applied force and takes place in the direction opposite to the force

Question 13
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According to the law of conservation of momentum,

A
the momentum of an isolated system of interacting particles is conserved.

B
the total momentum of an interacting system of particles and fields is conserved.

C
the total momentum of an isolated system of interacting particles is conserved.

D
the momentum of an interacting system of particles and fields is conserved.

Question 14
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A constant retarding force of 50 N is applied to a body of mass 20 kg moving initially with a speed of 15 m s⁻¹How long does the body take to stop?

A
1.7 s

B
6.0 s

C
5.0 s

D
none

Question 15
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A man of mass 70 kg stands on a weighing scale in a lift which is moving upwards with a uniform acceleration of 5 ms⁻² what would be the reading on the scale?

A
125 kg

B
105 kg

C
95 kg Hz

D
115 kg

Question 16
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A monkey of mass 40 kg climbs on a rope which can stand a maximum tension of 600 N. What is the tension in the rope if the monkey climbs up with an acceleration of 6 ms⁻²

A
640 N

B
600 N

C
760 N

D
740 N

Question 17
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Force is a

A
quantitative measure of the momentum between two bodies.

B
qualitative measure of the momentum of two bodies.

C
qualitative measure of the interaction between two bodies.

D
quantitative measure of the interaction between two bodies.

Question 18
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When bodies are in contact with each other then

A
contact forces are equal and in same direction.

B
contact forces are not equal and in same direction.

C
contact forces are equal and opposite in direction.

D
contact forces are not equal and opposite in direction.

Question 19
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A rocket with a lift-off mass 20,000 kg is blasted upwards with an initial acceleration of 5.0 ms^-2. Calculate the initial thrust (force) of the blast.

A
365000 N

B
378000 N

C
300000 N

D
350000 N

Question 20
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Two bodies of masses 10 kg and 20 kg respectively kept on a smooth, horizontal surface are tied to the ends of a light string. a horizontal force F = 600 N is applied to the 20 kg mass so as to pull it. What is the tension in the string?

A
250 N

B
300 N

C
150 N

D
200 N

Question 21
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A monkey of mass 40 kg climbs on a rope which can stand a maximum tension of 600 N. What is the tension in the rope if the monkey climbs down with an acceleration of 4 ms⁻²

A
200 N

B
300 N

C
240 N

D
280 N

Question 22
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When several forces act on a body

A
the effect on its motion is the same as when a single force acts on the body

B
the effect on its motion is the same as when a single force, equal to the vector sum (resultant) of the forces, acts on the body

C
the effect on its motion is the same as when a single force, not equal to the vector sum (resultant) of the forces, acts on the body

D
none

Question 23
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Friction is

A
perpendicular to contact surface and aids motion

B
parallel to contact surface and aids motion

C
perpendicular to contact surface and opposes i motion

D
parallel to contact surface and opposes the relative motion

Question 24
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A truck starts from rest and accelerates uniformly at 2.0 ms⁻². At t = 10 s, a stone is dropped by a person standing on the top of the truck (6 m high from the ground). What is the magnitude of acceleration (in ms⁻² ) of the stone at t = 11s? (Neglect air resistance.)

A
8

B
14

C
10.0

D
12

Question 25
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A monkey of mass 40 kg climbs on a rope which can stand a maximum tension of 600 N. What is the tension in the rope if the monkey climbs up with a uniform speed of 5 ms⁻¹

A
400 N

B
315 N

C
206 N

D
275 N

Question 26
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A stationary ball weighing 0.25kg acquires a speed of 10m/s when hit by a hockey stick. The impulse imparted to the ball is

A
1.5 Ns

B
0.5 Ns

C
2.5 Ns

D
2.0 Ns

Question 27
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Static friction force

A
increases until the body starts to move.

B
decreases before moving and increases later.

C
remains constant.

D
is a strong interaction force.

Question 28
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A bob of mass 0.1 kg hung from the ceiling of a room by a string 2 m long is set into oscillation. The speed of the bob at its mean position is 1 ms⁻¹. What is the trajectory of the bob if the string is cut when the bob is at one of its extreme positions

A
bob will go upwards

B
bob will fall vertically downwards

C
bob will go downwards at an angle

D
bob will go down in a parabolic path

Question 29
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If second law is applied to a rigid body

A
the acceleration is that of the centre of mass

B
the acceleration is the average of all particles in the body

C
the acceleration is that of any particle in the body

D
none of the above

Question 30
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Rolling friction is

A
greater than or equal to static

B
greater than static friction

C
equal to static friction

D
less than static friction

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Question Analysis

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Laws Of Motion ...

Question 1

The stone flies off at an angle with the tangent whose magnitude depends on the speed of the particle.

The stone moves radially inwards.

The stone flies off tangentially from the instant the string breaks.

The stone moves radially outwards.

Question 2

105 kg

75 kg

70 kg

35 kg

Question 3

0.1 N along the direction of motion

0.2 opposite to the direction of motion

0.1 N opposite to the direction of motion

1.0 N in the direction of motion

Question 4

they exert forces on each other that at each instant are equal in magnitude and opposite in direction.

they exert forces on each other that at each instant are equal in magnitude and same in direction.

they exert forces on each other that at some instants are equal in magnitude and opposite in direction.

they exert forces on each other that at some instants are equal in magnitude and same in direction.

Question 5

to start a stationary object and to stop a moving object.

only to keep an object moving.

only to stop a moving object.

only to start a stationary object moving.

Question 6

not equal in magnitude and opposite in direction

not equal in magnitude and same in direction

equal in magnitude and same in direction

equal in magnitude and opposite in direction

Question 7

body acted on by no net force moves with increasing velocity and negative acceleration

body acted on by no net force moves with constant velocity (which may be zero) and zero acceleration

body acted on by net force moves with constant velocity (which may be zero)

body acted on by zero net force moves with non zero acceleration

Question 8

1.0 N in the direction of motion

0.1 N opposite to the direction of motion

0.1 N along the direction of motion

0.2 opposite to the direction of motion

Question 9

150 kg

120 kg

130 kg

140 kg

Question 10

3000 N upward

4500 N upward

7500 N upward

1500 N upward

Question 11

27∘

37∘

42∘

32∘

Question 12

The momentum of a body is directly proportional to the applied force and takes place in the direction in which the force acts

The change of momentum of a body is directly proportional to the applied force and takes place in the direction in which the force acts

The rate of change of momentum of a body is directly proportional to the applied force and takes place in the direction in which the force acts

The momentum of a body is directly proportional to the applied force and takes place in the direction opposite to the force

Question 13

the momentum of an isolated system of interacting particles is conserved.

the total momentum of an interacting system of particles and fields is conserved.

the total momentum of an isolated system of interacting particles is conserved.

the momentum of an interacting system of particles and fields is conserved.

Question 14

1.7 s

6.0 s

5.0 s

none

Question 15

125 kg

105 kg

95 kg Hz

115 kg

Question 16

640 N

600 N

760 N

27^∘

37^∘

42^∘

32^∘