## Force And Laws Of Motion Multiple Choice Questions

**Direction:** Choose the correct option for each questions. There is only one correct response for each question.

**Question 1. Choose the S.I. unit of force**

- cm/s
- Newton
- m/s
- km/s

**Answer.** 2. Newton

**Question 2. Which among the following are the types of inertia?**

- Rest
- Motion
- Direction
- Volume

**Answer.** 4. Volume

**Question 3. Which law of Newton states that ‘Every action has an equal and opposite reaction’?**

- First law of motion
- Second law of motion
- Third law of motion
- Fourth law of motion

**Answer.** 3. Third law of motion

**Question 4. If a train starts suddenly in the forward direction, passengers standing in the train will fall ______.**

- Backwards
- Forward
- Sideways
- Downwards

**Answer.** 1. Backwards

**Question 5. Rate of change of momentum is equal to ______.**

- Work done
- Acceleration
- Speed
- Force

**Answer.** 4. Force

**Question 6. kg.m/s2 is the unit of _____.**

- Force
- Speed
- Velocity
- Acceleration

**Answer.** 1. Force

**Question 7. A car is running with a force of 5 N. The weight of car is 0.5 kg. What is the acceleration?**

- 5
- 10
- 15
- 20

**Answer.** 2. 10

**Question 8. The principle in which jet engine works on is _______.**

- Conservation of mass
- Conservation of momentum
- Newton’s first law of motion
- Newton’s Second law of motion

**Answer.** 2. Conservation of momentum

**Question 9. Inertia is a property of an object by virtue of which object is _______ .**

- Not able to change its state of rest or uniform motion in a straight line
- Not able to change its state of rest
- Not able to change its direction of motion
- Not able to change its state of uniform motion in a straight line

**Answer.** 1. Not able to change its state of rest or uniform motion in a straight line

**Question 10. When a net force acts on an object, the object will be accelerated in the direction of force with acceleration proportional to ______ of the object.**

- Speed
- Velocity
- Acceleration
- Force

**Answer.** 4. Force

**Question 11. When an object undergoes acceleration, ___________.**

- Speed decreases
- Speed increases
- Force is acting on it
- Object falls on ground

**Answer.** 3. Force is acting on it

**Question 12. Force can be defined from ______.**

- Newton’s first law of motion
- Newton’s second law of motion
- Newton’s third law of motion
- Newton’s fourth law of motion

**Answer.** 1. Newton’s first law of motion

**Question 13. If A and B are two objects of masses 10 kg and 20 kg respectively, then which among the following statement is correct?**

- A has more inertia than B
- B has more inertia than A
- A and B has same inertia
- None of the Above

**Answer.** 2. B has more inertia than A

**Question 14. An object moves with constant acceleration if constant ______ is applied on the object.**

- Speed
- Velocity
- Force
- Acceleration

**Answer.** 3. Force

**Question 15. One Newton is the force equal to ______.**

- Gravity on 1 kg object
- Mass of 1 kg and acceleration of 1 m/s2
- Mass of 1 g and acceleration of 1 cm/s2
- Gravity on 1 g object

**Answer.** 2. Mass of 1 kg and acceleration of 1 m/s2

**Question 16. A man tosses a coin in a moving train and the coin falls behind him. It shows that the train is ______.**

- Accelerated
- Retarded
- Uniform
- Moving in circular track

**Answer.** 1. Accelerated

**Question 17. A car of mass 20 kg is moving with an acceleration of 2 m/s2. What is the rate of change of momentum?**

- 10
- 20
- 30
- 40

**Answer.** 4. 40

**Question 18. An object is moving in a straight line in an acceleration motion. Choose the incorrect statement related to the statement.**

- Velocity keeps changing
- Speed keeps changing
- Object goes away from the earth
- Force is always acting on object

**Answer.** 3. Object goes away from the earth

**Question 19. Rocket works on the principle of conservation of _______.**

- Speed
- Velocity
- Energy
- Momentum

**Answer.** 4. Momentum

**Question 20. As per the third law of motion, action and reaction _______.**

- Always act on different objects in opposite direction
- Always act on same body in opposite direction
- Always act on same body in same direction
- Always act on same body

**Answer.** 1. Always act on different objects in opposite direction

**Question 21. A goalkeeper on holding the football pulls his hand backwards because it helps the goalkeeper to ______.**

- Increase rate of change of momentum
- Decrease rate of change of momentum
- Exert larger force on football
- Reduce force exerted by ball on hand

**Answer.** 4. Reduce force exerted by ball on hand

**Question 22. An athlete before doing long jump, runs for some distance because ______.**

- Helps in applying large force
- Action and reaction force increases
- Gives him larger inertia of motion
- Gains energy

**Answer.** 3. Gives him larger inertia of motion

**Question 23. While riding a horse, the rider falls back when the horse starts because the ______.**

- Rider is afraid of falling back
- Rider is taken back
- Inertia of rest keeps the upper part of body at rest while lower part of body moves forward with the horse
- Inertia of rest keeps the lower part of body at rest while upper part of body moves forward with the horse

**Answer.** 3. Inertia of rest keeps the upper part of body at rest while lower part of body moves forward with the horse

**Question 24. The property of inertia is more in ______.**

- Toy car
- Car
- Truck
- Horse cart

**Answer.** 4. Horse cart

**Question 25. A boy has a tennis ball and a football at rest. In order to move it, which among the following is correct**

- Same force is required for both
- More force is required for football ball
- More force is required for tennis ball
- No force is required to move the balls

**Answer.** 2. More force is required for football ball

**Question 26. Which among the following is the equation for second law of motion?**

- F = ma
- F = mv
- F = av
- F = mav

**Answer.** 1. F = ma

**Question 27. When a running car stops suddenly, passenger tends to fall ______.**

- Forward
- Backward
- Sideways
- Downside

**Answer.** 1. Forward

**Question 28. ______ is an external cause which can move a still object to move and can stop a moving object.**

- Force
- Speed
- Velocity
- Acceleration

**Answer.** 1. Force

**Question 29. Force is a ______ quantity**

- Scalar
- Vector
- Both
- None of the above

**Answer.** 2. Vector

**Question 30. Inertia of an object depends on ______.**

- Force
- Speed
- Velocity
- Mass

**Answer.** 4. Mass

**Question 31. On applying equal and opposite forces on an object, the object will.**

- Move left
- Move right
- Doesn’t move
- Move up

**Answer.** Doesn’t move

**Question 32. The unit of Linear momentum is ______.**

- Ns
- N/s
- kg/s
- g/s

**Answer.** 1. Ns

**Question 33. The correct form of Newton’s second law of motion is ______.**

- F = \(\frac{\Delta p}{\Delta t}\)
- F = \(m\left(\frac{\Delta v}{\Delta t}\right)\)
- \(F=v\left(\frac{\Delta m}{\Delta t}\right)\)
- F = mv

**Answer.** 1. F = \(\frac{\Delta p}{\Delta t}\)

**Question 34. The C.G.S. unit of force is ______.**

- Newton
- Dyne
- kg/m
- m/s

**Answer.** 2. Dyne

**Question 35. Which law states that ’When an object is at rest it will remain at rest and if it is moving, it will continue to move in the same direction unless an external force is applied on it‘.**

- Newton’s first law of motion
- Newton’s second law of motion
- Newton’s third law of motion
- Newton’s fourth law of motion

**Answer.** 1. Newton’s first law of motion

**Question 36. Newton’s first law of motion is discussed through the definition of ______.**

- Inertia
- Force
- Speed
- Acceleration

**Answer. **

2. Force

3. Speed

**Question 37. Which among the following are the unit of Force?**

- kg/m
- Newton
- Dyne
- m/s

**Answer. **

3. Newton

4. Dyne

**Question 38. Choose the correct statement:**

- If an object is at rest it will remain at rest until an external force is applied.
- If an object is moving, it will continue to move until an external force is applied.
- If an object is at rest it will remain at rest even after applying external force.
- If an object is moving it will continue moving even after applying external force.

**Answer.**

1. If an object is at rest it will remain at rest until an external force is applied.

4. If an object is moving it will continue moving even after applying external force.

**Question 39. Newton’s third law of motion states that ‘For every action there is an equal and ______ reaction’.**

- Equal
- less
- Greater
- Opposite

**Answer.**

1. Equal

4. Opposite

**Question 40. Choose the incorrect equation:**

- 1 N = 1 kg.m/s
^{2} - F = m a
- a = \(\frac{v}{t}\)
- a = v – u

**Answer. **

3. a = \(\frac{v}{t}\)

4. a = v – u

**Question 41. Choose the correct statement:**

- The inertia of an object tends to cause the object to resist any change in its state of motion.
- Inertia is a property of an object by the virtue of which an object is unable to change by itself the state of rest or uniform motion in a straight line.
- Inertia is a property of an object by the virtue of which an object is able to change by itself the state of rest or uniform motion in a straight line.
- The inertia of an object tends to cause the object to resist no change in its state of motion.

**Answer.**

- The inertia of an object tends to cause the object to resist any change in its state of motion.
- Inertia is a property of an object by the virtue of which an object is unable to change by itself the state of rest or uniform motion in a straight line.

**Question 42. Choose the correct statement:**

- When a train starts suddenly, passengers standing in the train tend to fall backwards.
- When a train starts suddenly, passengers standing in the train tend to fall forward.
- When a train stops suddenly, passengers standing in the train tend to fall forward.
- When a train stops suddenly, passengers standing in the train tend to fall backwards.

**Answer. **

1. When a train starts suddenly, passengers standing in the train tend to fall backwards.

3. When a train stops suddenly, passengers standing in the train tend to fall forward.

**Question 43. Which of the following statement is correct for an object moving along a straight line in an accelerated motion?**

- Speed keeps changing
- Velocity always change
- It goes away from earth
- Force is acting on it

**Answer. **

1. Speed keeps changing

2. Velocity always change

4. Force is acting on it

**Question 44. Choose the incorrect statement. According to the newton’s third law of motion, action and reaction ______.**

- Acts on same object in the same direction
- Acts on different object in the same direction
- Acts on different object in opposite direction
- Acts on same object in different direction

**Answer. **

1. Acts on same object in the same direction

2. Acts on different object in the same direction

4. Acts on same object in different direction

**Question 45. Choose the incorrect statement:**

- Rocket works on the principle of conservation of momentum.
- Rocket works on the principle of conservation of mass.
- Rocket works on the principle of conservation of energy.
- Rocket works on the principle of conservation of velocity.

**Answer. **

2. Rocket works on the principle of conservation of mass.

3. Rocket works on the principle of conservation of energy.

4. Rocket works on the principle of conservation of velocity.

**Question 46. A body at rest breaks into two pieces of equal masses. The parts will move**

- in same direction
- along different lines
- in opposite directions with equal speeds
- in opposite directions with unequal speeds

**Answer.** 3. in opposite directions with equal speeds

**Question 47. When a bus starts suddenly, the passengers standing inside leans backwards. This is an example of**

- Newton’s first law of motion
- Newton’s second law of motion
- Newton’s third law of motion
- Law of conservation of momentum

**Answer.** 1. Newton’s first law of motion

**Question 48. A block of mass 2 kg is sliding with a constant velocity of 8 m/s on a frictionless horizontal surface. The force exerted on the horizontal surface is nearly**

- 20 N
- 10 N
- 40 N
- 16 N

**Answer.** 1. 20 N

**Question 49. A machine gun fires n bullets per second, each of mass m. If the speed of each bullet is u, then the force of recoil i**

- mng
- mnv
- mnvg
- (mnv)/g

**Answer.** 2. mnv

**Question 50. A force of 5 N acts on a body of weight 9.8 N. What is the acceleration produced in m/s ^{2}**

- 0.51
- 1.96
- 5.00
- 49.00

**Answer.** 3. 5.00

**Question 51. In a game of tug of war, a condition of equilibrium exists. Both the teams pull the rope with a force of 104 N. Tension in the rope is**

- 10
^{4}N - 10
^{8}N - 2 × 10
^{4}N - zero

**Answer.** 1. 10^{4} N

**Question 52. The action and reaction forces referred to in Newton’s third law of motion**

- must act on same body
- must act on different bodies
- need not be equal in magnitude but must have the same line of action
- must be equal in magnitude but need not have the same line of action

**Answer.** 2. must act on different bodies

**Question 53. You are marooned on the frictionless horizontal plane and cannot exert any horizontal force by pushing against the surface. How can you get off?**

- By running on the plane
- By jumping
- By rolling your body on the surface
- By sneezing or spitting

**Answer.** 3. By rolling your body on the surface

**Question 54. Choose the wrong statement of the following**

- 1 kg wt = 9.8 N
- Momentum is a vector quantity
- Force is always conserved
- Momentum is conserved in the absence of an external force

**Answer.** 3. Force is always conserved

**Question 55. A long-jumper runs before jumping because**

- he covers a greater distance
- he maintains momentum conservation
- he gains energy by running
- he gains momentum

**Answer.** 4. he gains momentum

**Question 56. A man is standing on a boat in still water. If he walks towards the shore the boat will**

- move away from the shore
- remain stationary
- move towards the shore
- sink

**Answer.** 1. move away from the shore

**Question 57. A body of mass 300 gm is at rest. What force in Newton will you have to apply to move it through 200 cm in 10 sec.?**

- Zero
- 12 Newton
- 1.2 Newton
- 0.12 Newton

**Answer.** 4. 0.12 Newton

**Question 58. A boat of mass 3000 kg, initially at rest is pulled by a force of 1.8 × 104 Newton through a distance of 3 m. Assuming that the resistance due to water is negligible, velocity of boat is**

- 6 m/s
- 8 m/s
- 9 m/s
- 11 m/s

**Answer.** 1. 6 m/s

**Question 59. A certain force applied to mass m**_{1 }**gives it an acceleration of 15 m/s ^{2}. The same force is applied on**

**m**

_{2}to give it acceleration of 10 m/s^{2}, if the two masses are fixed together and the same force is applied to the combination, then the acceleration will be- 6 m/s
^{2} - 8 m/s
^{2} - 9 m/s
^{2} - 11 m/s
^{2}

**Answer.** 1. 6 m/s^{2}

**Question 60. A bullet of mass A and velocity B is fired into a block of wood of mass C. If loss of any mass and friction be neglected, then velocity of the system must be**

- \(\frac{A B}{A+C}\)
- \(\frac{A+C}{B+C}\)
- \(\frac{A C}{B+C}\)
- \(\frac{A+B}{A C}\)

**Answer.** 1. \(\frac{A B}{A+C}\)

**Question 61. A driver accelerates his car first at the rate of 18 m/s2 and then the rate of 12 m/s2 . The ratio of the forces exerted by the engines respectively will be**

- 2 : 3
- 1 : 2
- 2 : 1
- 3 : 2

**Answer.** 1. 2 : 3

**Question 62. A body of mass 5 kg undergoes a change in speed from 30 to 40 m/s. Its momentum would increase by**

- 50 kg m/s
- 75 kg m/s
- 150 kg m/s
- 350 kg m/s

**Answer.** 1. 50 kg m/s

**Question 63. A body of mass 5 kg undergoes a change in speed from 20 to 0.20 m/s. The momentum of the body would**

- increase by 99 kg m/s
- decrease by 99 kg m/s
- increase by 101 kg m/s
- decrease by 101 kg m/s

**Answer.** 2. decrease by 99 kg m/s

**Question 64. A body of mass 100 g is moving with a velocity of 15 m/s. The momentum associated with that ball will be**

- 0.5 kg m/s
- 1.5 kg m/s
- 2.5 kg m/s
- 3.2 kg m/s

**Answer.** 2. 1.5 kg m/s

**Question 65. A stationary ball weighing 0.25 kg acquires a speed of 10 m/s when hit by a hockey stick. The impulse imparted to the ball is**

- 2.5 N s
- 2.0 N s
- 1.5 N s
- 0.5 N s

**Answer.** 1. 2.5 N s

**Question 66. Momentum is a measure** **of**

- weight
- mass
- quantity of motion
- velocity

**Answer.** 3. quantity of motion

**Question 67. It is difficult to walk on ice because of**

- absence of friction
- absence of inertia
- more inertia
- more friction

**Answer.** 1. absence of friction

**Question 68. A and B are two objects with mass 6 kg and 34 kg respectively. Then**

- A has more inertia than B
- B has more inertia than A
- A and B both have same inertia
- None of these

**Answer.** 2. B has more inertia than A

**Question 69. When a body is stationary**

- there is no force acting on it
- the forces acting on it are not in contact with it
- the combination of force acting on it balanced each other
- the body is in vacuum

**Answer.** 3. the combination of force acting on it balanced each other

**Question 70. Which of the following represents the SI unit of force?**

- dyne
- gram-weight
- newton
- kilogram-weight

**Answer.** 3. newton

**Question 71. When a constant force is applied to a body, it moves with uniform**

- acceleration
- velocity
- speed
- momentum

**Answer.** 1. acceleration

**Question 72. Passengers standing in a bus are thrown outwards when the bus takes a sudden turn, due to**

- outward pull on them
- inertia
- change in momentum
- change in acceleration

**Answer.** 2. inertia

**Question 73. A body of mass M collides against a wall with velocity V and rebounds with the same speed. Its change of momentum is**

- zero
- MV
- 2 MV
- –MV

**Answer.** 3. 2 MV

**Question 74. Tyres are made circular because**

- they can be inflated
- they require less material
- they look beautiful
- they face less friction

**Answer.** 4. they face less friction

**Question 75. For a 1 kg mass v-t graph is as shown, then which of the following is true?**

- force between A and B ≠ force between C and D
- force between A and B = force between C and D
- force between B and C = 1
- data insufficient to calculate the force

**Answer.** 1. force between A and B ≠ force between C and D

**Question 76. Two forces of 6N and 3N are acting on the two blocks of 2kg and 1kg kept on frictionless floor. What is the force exerted on 2kg block by 1 kg block?**

- 1 N
- 2 N
- 4 N
- 5 N

**Answer.** 3. 4 N

**Question 77. Three masses of 1 kg, 6 kg and 3 kg are connected to each other with threads and are placed on table as shown in figure, What is the acceleration with which the system is moving? Take g = 10 m s ^{-2}.**

- Zero
- 1 m s
^{-2} - 2 m s
^{-2} - 3 m s
^{-2}

**Answer.** 3. 2 m s^{-2}

**Question 78. Two blocks of mass 4 kg and 2 kg are connected by a heavy string and placed on rough horizontal plane. The 2 kg block is pulled with a constant force F. The coefficient of friction between the blocks and the ground is 0.5. What is the value of F so that tension in the string is constant throughout during the motion of the blocks: (g = 10 m/s ^{2})**

- 40 N
- 30 N
- 50 N
- 60 N

**Answer.** 2. 30 N

**Question 79. A string of negligible mass going over a clamped pulley of mass m supports a block of mass M as shown in the figure. The force on the pulley by the clamp is given by**

- \(\sqrt{2}\) Mg
- \(\sqrt{2}\) mg
- \(\left(\sqrt{(M+m)^2+m^2}\right) g\)
- \(\left(\sqrt{(M+m)^2+M^2}\right) g\)

**Answer.** 4. \(\left(\sqrt{(M+m)^2+M^2}\right) g\)

## Force And Laws Of Motion Track Your Learning Question And Answers

**Question 1. If an object is still, it will remain still and if it is moving it will remain moving until an external force is applied. This is called ______.**

- Newton’s first law of motion
- Newton’s second law of motion
- Newton’s third law of motion
- Newton’s fourth law of motion

**Answer.** 1. Newton’s first law of motion

**Question 2. An object moving in a straight line will continue to move in the same direction until and unless some external force compels it to change the direction of motion. This is called ______.**

- Inertia of motion
- Inertia of direction
- Inertia of speed
- Inertia of velocity

**Answer.** 2. Inertia of direction

**Question 3. ______ is the external cause which tends to change the state of rest or the state of motion of an object.**

- Velocity
- Speed
- Force
- Acceleration

**Answer.** 3. Force

**Question 4. S.I. unit of inertia is ______.**

- t
- kg
- g
- m

**Answer.** 2. kg

**Question 5. _____ is the measure of inertia of a body at rest.**

- Mass
- Time
- Acceleration
- Speed

**Answer.** 1. Mass

## Force And Laws Of Motion Track Your Learning Question And Answers

**Question 1. C.G.S. unit of force is ______.**

- Newton
- Dyne
- kg
- m/s

**Answer.** 2. Dyne

**Question 2. Choose the correct equation**

- F = m a
- F = m/a
- F = m t
- F = mv

**Answer.** 1. F = m a

**Question 3. When a glass falls on floor, it ______.**

- Jumps
- Moves backward
- Moves forward
- Breaks

**Answer.** 4. Breaks

**Question 4. S.I. unit of momentum is ______.**

- kgm/s
- cm m/s
- m/s
- g cm/s

**Answer**. 1. kg m/s

**Question 5. C.G.S. unit of momentum is ______.**

- kg m/s
- cm m/s
- m/s
- g cm/s

**Answer.** 4. g cm/s

## Force And Laws Of Motion Practice Exercises

**Question 1. Which of the following statement is not correct for an object moving along a straight path in an accelerated motion?**

- Its speed keeps changing
- Its velocity always changes
- It always goes away from the earth
- A force is always acting on it

**Answer.** 3. It always goes away from the earth

**Question 2. According to the third law of motion, action and reaction**

- always act on the same body
- always act on different bodies in opposite directions
- have same magnitude and directions
- act on either body at normal to each other

**Answer.** 2. always act on different bodies in opposite directions

**Question 3. A goalkeeper in a game of football pulls his hands backwards after holding the ball shot at the goal. This enables the goal keeper to**

- exert larger force on the ball
- reduce the force exerted by the ball on hands
- increase the rate of change of momentum
- decrease the rate of change of momentum

**Answer.** 2. reduce the force exerted by the ball on hands

**Question 4. The inertia of an object tends to cause the object**

- to increase its speed
- to decrease its speed
- to resist any change in its state of motion
- to decelerate due to friction

**Answer.** 3. to resist any change in its state of motion

**Question 5. A passenger in a moving train tosses a coin which falls behind him. It means that motion of the train is**

- accelerated
- uniform
- retarded
- along circular tracks

**Answer.** 1. accelerated

**Question 6. An object of mass 2 kg is sliding with a constant velocity of 4 ms**^{-1}**on a frictionless horizontal table. The force required to keep the object moving with the same velocity is**

- 32 N
- 0 N
- 2 N
- 8 N

**Answer.** 2. 0 N

**Question 7. Rocket works on the principle of conservation of**

- mass
- energy
- momentum
- velocity

**Answer.** 3. momentum

**Question 8. A water tanker filled up to 2/3 of its height is moving with a uniform speed. On sudden application of the brake, the water in the tank would**

- move backward
- move forward
- be unaffected
- rise upwards

**Answer.** 2. move forward

**Question 1. Which among the following is not an unbalanced force?**

- Stop a moving object
- Two boys playing on a see-saw
- Arm-wrestling competition
- Pushing an object from both sides

**Answer.** 4. Pushing an object from both sides

**Question 2. ________ is the force acting parallel to the surface of the contact.**

- Inertia
- Balanced Force
- Unbalanced Force
- Frictional force

**Answer.** 2. Balanced Force

**Question 3. If one object applies more force than the other one it is called _____ force.**

- Inertia
- Balanced
- Unbalanced
- Linear

**Answer.** 3. Unbalanced