# MCQ of Laws of Motion | Chapter 5 | Physics | Class 11 | CBSE |

MCQ of Laws of Motion, Chapter 5, Physics, Class 11

Multiple Choice Questions of Laws of Motion, Chapter 5, Physics, Class 11

Question 1 : Who used the term inertia for the first time ?

1. Newton
2. Galileo
3. Aristotle
4. Kepler

Answer : B ( Galileo )

Question 2 : Which of the following statements precisely explain inertia

1. Inertia is that property of body by the virtue of which the body is unable to change by itself the state of rest
2. Inertia is that property of body by the virtue of which the body is unable to change by itself the state of uniform motion .
3. Inertia is that property of body by the virtue of which the body is unable to change by itself the direction of motion.
4. Inertia is that property of the body by the virtue of which the body is unable to change by itself the state of rest or of uniform motion .

Answer : D ( Inertia is that property of the body by the virtue of which the body is unable to change by itself the state of rest or of uniform motion . )

Question 3 : A passenger is travelling in a bus while he was getting down , he fall in the direction of motion of bus . This condition is satisfied by

1. Second law of motion sticks to this condition
2. Third law of motion sticks to this condition .
3. Inertia of rest
4. Inertial of motion

Answer : D ( Inertia of motion )

Question 4 : A spherical ball is travelling with a uniform translatory motion then which of the following is accurate ?

1. The ball is at rest
2. The spherical ball is travelling with a uniform speed in a straight or circular path .
3. All the parts of the spherical ball are moving with a constant velocity .
4. The ball spins about its Centre uniformly and the center of the ball moves with a constant velocity .

Answer : C ( All the parts of the spherical ball are moving with a constant velocity . )

Question 5 : When a speeding bus stops immediately then the passengers experiences a certain jerk and are thrown forward from their seats because

1. When the bus stops the back of feet suddenly pushes the passengers forward
2. When the bus stops immediately due to inertia of rest it takes the body forward
3. When the bus stops immediately the upper part of body continues to be in the state of motion whereas the lower part of the body remain in contact with the seat remains at rest due to which a certain jerk is experienced by a passenger
4. When the bus stops immediately then the upper part of the body comes to rest whereas the lower part of the body comes in contact with the seat and begin to move that’s why the person experiences a certain jerk.

Answer : C ( When the bus stops immediately the upper part of body continues to be in the state of motion whereas the lower part of the body remain in contact with the seat remains at rest due to which a certain jerk is experienced by a passenger )

Question 6 : Physical independence of force is an outcome of which law of motion

1. It is an outcome of first law of motion
2. It is an outcome of second law of motion
3. It is an outcome of third law of motion
4. It is an outcome of all these laws of motion

Answer : A ( It is an outcome of first law of motion )

Question 7 : An astronaut accidentally get detached from his small spaceship accelerating in the interstellar space with a constant rate of 100 ms-2 . What shall be the acceleration of the astronaut at the instant after he was detached from his spaceship in the interstellar space.
Given that there are no nearby stars to exert gravitational force neither on the astronaut nor on the spaceship .

1. At the instant he was detached , his acceleration was zero .
2. At the instant he was detached , his acceleration was 10ms-2.
3. At the instant he was detached , his acceleration was 50ms -2.
4. At the instant he was detached , his acceleration was 100ms-2.

Answer : A ( At the instant he was detached , his acceleration was zero .)

Question 8 : Which of the following statements is inaccurate about the Newton’s second law of motion and that is F=ma

1. The second law of motion is compatible with the first law of motion
2. The second law of motion is a vector based law
3. The second law of motion is significant for a single point particle
4. The second law of motion is not localized .

Answer D ( The second law of motion is not localized .)

Question 9 : The expression F= ma can never be deduced from Newton’s second law if

1. This is the only condition when force depends on time
2. This is the condition when momentum depends on time
3. This is the condition when acceleration depends on time
4. This is the condition when mass depend on time

Answer D : ( This is the condition when mass depend on time )

Question 10 : Which of the following is not an appropriate form of force

1. Impulse
2. Tension
3. Thrust
4. Weight

Answer : A ( Impulse )

You may also read MCQ of Physical World, MCQ of Units and Measurements, MCQ of Motion in a Straight Line, MCQ of Motion in a Plane, MCQ of Work, Energy and Power, MCQ of System of Particles and Rotational Motion, MCQ of Gravitation for better understanding of the chapters.

Question 11 : A particle of mass ‘m’ travels with a certain initial velocity ‘u’ and covers a displacement of ‘y’ units in time ‘t’ . The expression is given as
y=ut+1/2 (gt2).
Then find the amount of force acting on the particle

1. mg
2. mu/t
3. 2 m g
4. 2 m u/t

Answer : A ( mg )

Question 12 : A body of mass 5 kg changes its speed from 5m/s to 10m/s without changing the direction of the most on what will be the amount of force acting on the body ?

1. 1.5 N
2. 2 N
3. 2.5 N
4. 5 N

Answer : C ( 2.5 N )

Question 13 : A body experiences a force of 6 i^ – 8 j^ requires a certain acceleration of 5 ms-2 then the mass of body is ?

1. Mass of body is 2 Kg
2. Mass of body is 5 Kg
3. Mass of body is 4 Kg
4. Mass of body is 6 Kg

Answer : A ( Mass of body is 2 Kg )

Question 14 : A ball of mass m hits a rigid wall with speed u and come back mister same speed then how much impulse will be imparted to the ball by the wall

1. 2 m u
2. mu
3. Zero
4. -2 m u

Answer : d ( -2 m u )

Question 15 : The driver of a car suddenly observe a broad wall in front of him in this condition what should he do ?

1. He Should break sharply
2. He should turn sharply
3. Both a and b
4. None of these

Answer : A ( He Should break sharply )

Question 16 : Which of the following statements in appropriate about the laws of motion

1. A cricketer moves his hand rearwards while holding a catch
2. A person falling from a certain height gets more injuries When he falls on a cemented floor rather than if he falls on a heap of sand
3. It is quite easier to push in lawn mower then to pull it
4. Mountain roads are made quite winding upwards rather than going straight .

Answer C : ( It is quite easier to push in lawn mower then to pull it )

Question 17 : Which of the following forces is categorized as a self adjusting force

1. Static friction is a self adjusting force
2. Rolling friction is a self adjusting force
3. Sliding friction is a self adjusting force
4. Dynamic friction is a self adjusting force

Answer : A ( Static friction is a self adjusting force )

Question 18 : Which of the following can act as lubricant in the appliances ?

1. Iron feelings can act as lubricant in the machines
2. Polish on machines is on another way to lubricate
3. By flowing water through a machine can act as a good lubricant
4. By following the compressed and purified air via appliances can act as lubricant

Answer : D ( By following the compressed and purified air via appliances can act as lubricant )

Question 19 : A driver is driving a car , what can be the reason of the acceleration of the car on a horizontal road

1. The car accelerates due to the force exerted by the engine of the car
2. The car accelerates due to the force exerted by the driver of the car
3. The car accelerates due to the force exerted by the car on the earth
4. The car accelerates due to the force exerted by the road on the car

Answer : D ( The car accelerates due to the force exerted by the road on the car )

Question 20 : A block of mass M is placed on a inclined place . What is the angle of inclination of the plane to the horizontal when the block will start to slide down the plane given that the coefficient of friction of the surface is ‘u’

1. θ = tan-1 μ
2. θ = cos-1 μ
3. θ = sin-1 μ
4. θ= sec-1μ

Answer : A ( θ= tan-1 u )

Question 21 : A girl presses her chemistry book against the vertical wall with her hand then what will be the direction of force exerted by the wall on the book ?

1. The direction of force is downwards
2. The direction of force is upward
3. The direction of force is out from the wall
4. Direction of force is into the wall

Answer : B ( The direction of force is upward )

Question 22 : Which of the following statements is accurate about the friction

1. The coefficient of friction depends on the area of contact between the surface and the object to a large extent
2. The frictional force can never be greater than the reaction force on the body from the support surface
3. Rolling friction is only slight less than the sliding friction
4. The main reason of friction is the irregularity of the surfaces in the contact

Answer :  A ( The main reason of friction is the irregularity of the surfaces in the contact )

Question 23 : A block of mass 10 Kg is placed on a horizontal surface if a force of 100 N is applied on it then what will be the acceleration of the block is given that the coefficient of friction is 0.5

1. The acceleration of block is 10 ms-2
2. The acceleration of block is 5 ms-2
3. The acceleration of block is 15 ms-2
4. The acceleration of block is 0.5 ms-2

Answer : B ( The acceleration of block is 5 ms-2)

Question 24 : A block of mass M is placed on a incline plane making an angle O with the horizontal such that tan θ = 2u if the minimum force required to start pushing a body up on that surface is F1 while the minimum force required to prevent it from sliding down is F2 then what will be the ratio of these two forces i.e. F1/F2

1. 4
2. 1
3. 2
4. 3

Answer : D ( 3 )

Question 25 : What will be the maximum acceleration of the train which is which is suitable for a box lying on its surface to remain stationary if the coefficient of static friction between the box and train’s floor is 0.2 .

1. Acceleration of train is 2 ms-2
2. Acceleration of train is 4 ms-2
3. Acceleration of train is 6 ms-2
4. Acceleration of train is 8 ms-2

Answer : A ( Acceleration of train is 2 ms-2 )

Question 26 : Why does a cyclist slightly bends by taking a turn

1. The cyclist do so to reduce the friction
2. The cyclist do so to generate required centripetal force
3. The cyclist do so to reduce the Apparent weight
4. The cyclist bends to reduce his pace

Answer : B ( The cyclist do so to generate required centripetal force )

Question 27 : An aircraft accomplishes a horizontal loop at a speed of 720 Km/hr via its wings then what will be the radius of the loop ?

1. The radius of loop is 14.8 Km
2. The radius of loop is 14.8 m
3. The radius of loop is 29.6 Km
4. The radius of loop is 29.6 m

Answer A : ( The radius of loop is 14.8 Km )

Question 28 : A person moving upward via accelerator throws a coin upward with the speed of 20 ms-2 then how much time will the coin take to fall back into his hand if the elevator is accelerating with an acceleration of 2 ms-2

1. The coin will fall back into his hand after 5/3 s
2. The coin will fall back into his hand after 3/10 s
3. The coin will fall back into his hand after 10/3 s
4. The coin will fall back into his hand after 3/5 s

Answer : C ( The coin will fall back into his hand after 10/3 s )

Question 29 : Two blocks of masses 12 KG and 8 kg are connected by massless string which passes over a frictionless pulley then what will be the acceleration of the system

1. g/4
2. g/5
3. g/8
4. g/6

Answer : B ( g/5 )

Question 30 : A book of of mass 1 kg  is lying on a table what is the angle between the action and the reaction taken place between the table and book

1. 45°
2. 90°
3. 180°

Answer : D ( 180° )

Questions 31 : A monkey of mass 40 kg climbs on a vertical rope which can withstand a tension of 500 N . Pick out the conditions in which the rope can break . ( Consider the rope to be massless )

1. If the monkey climbs up with an acceleration of 5 ms-2 then the rope can break
2. If the monkey climbs down with an acceleration of 5 ms-2 then the rope can break
3. If the monkey climbs with a uniform speed of 5 ms-2
4. If the monkey falls down the rope freely under gravity

Answer : A ( If the monkey climbs up with an acceleration of 5 ms-2 then the rope can break )
Question 32 : What is the acceleration produced in the mass of 1 Kg in the following figure

1. g/8 in downwards direction
2. g/2 in downwards direction
3. g/2 in upwards direction
4. g/4 in upwards direction

Answer : C ( g/2 in upwards direction )

Question 33 : A weighing scale is placed in a lift which is accelerating upwards with a uniform acceleration of 9ms-2. If a person of 50 kg is standing the weighing scale then what would be the reading of the weighing scale

1. The weighing scale will show a reading of 50 kg
2. The weighing scale will show a reading of 60 kg
3. The weighing scale will show a reading of 95 kg
4. The weighing scale will show a reading of 100 kg

Answer : C ( The weighing scale will show a reading of 95 kg )

Question 34 : A helicopter of mass 2000 Kg is going upward with an acceleration of of 15 ms-2 if the total mass of the crew and the passengers is 500 kg then which of the following statement is correct ?

(i) The force exerted by the crew members and passengers on the floor of helicopter is vertically downward with a magnitude is 1.25× 104 N .

(ii) The rotor of the helicopter exerts a force on the surrounding in vertically downward direction with a magnitude of 6.25×104

(iii) The surrounding exerts a force of 6.25 X 104 in vertically upward direction.

1. (i) and (ii)
2. (ii) and (iii)
3. (i) and (iii)
4. All the three

Answer : D ( All the three )

Question 35 : What is the maximum speed with which a cyclist can take a circular turn of radius 3 without skidding if the coefficient of friction between the tires and road is 0.1

1. √15 m/s
2. √3 m/s
3. √30 m/s
4. √10 m/s

Answer : B ( √3 m/s )

Question 36 : In a circus show a motorcyclist rides around the well with a round vertical wall and do not full down while riding because

1. In this condition the force of gravity disappears
2. During this the motorcyclist loses his weight some how
3. The motorcyclist is kept in this path due to to the force exerted by surrounding air
4. During this the frictional force of wall balances his weight

Answer : D ( During this the frictional force of wall balances his weight )

Question 37 : A box of mass 2 kg is placed on a rough inclined surface which makes an angle of 30° with the horizontal if the coefficient of friction between the block and the surface is 0.7 then what will be the frictional force acting on the block

1. 10.3
2. 23.8
3. 11.9
4. 6.3

Answer : C ( 11.9 )

Question 38 : Which of the following statements is incorrect about the conservation of momentum ?

1. Same  amount of force for the same time always causes pain scenes in the momentum for non – identical bodies
2. The rate of change of momentum is directly proportional to the applied force and always takes place in the direction of force.
3. If a heavier block and a light body are moving with the same speed then more amount of force is required to stop heavy block then a light body
4. The rate of change of momentum is inversely proportional to the force which is to be applied.

Answer : D ( During this the frictional force of wall balances his weight )

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