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NEET Physics: Newton’s Third Law of motion Practice Questions

15 free multiple-choice questions on Newton’s Third Law of motion (Laws of Motion) for NEET Physics, each with the correct answer and a step-by-step explanation. Attempt a question, then reveal the solution to check your reasoning.

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  1. Q1. According to Newton's Third Law of Motion, the action and reaction forces always act on which two bodies?

    • AThe same direction and same body
    • BThe same direction
    • CDifferent bodies
    • DThe same body
    Show answer & explanation

    Correct answer: C — Different bodies

    Action and reaction forces always act on two different interacting bodies.

  2. Q2. If a force F acts on object A and an equal and opposite force -F acts on object B, this scenario is governed by which law of motion?

    • ANewton's Third Law
    • BNewton's First Law
    • CNewton's Second Law
    • DLaw of Conservation of Momentum
    Show answer & explanation

    Correct answer: A — Newton's Third Law

    The principle that forces always occur in equal and opposite pairs acting on different bodies is the definition of Newton's Third Law of Motion.

  3. Q3. A stationary box is placed on a smooth horizontal floor. Which statement correctly describes the action and reaction forces involved?

    • AThe force exerted by the floor on the box is equal and opposite to the force exerted by the box on the floor.
    • BThe force exerted by the box on the floor is zero.
    • CThe force exerted by the floor on the box is less than the force exerted by the box on the floor.
    • DThe reaction force is entirely due to the box's inertia.
    Show answer & explanation

    Correct answer: A — The force exerted by the floor on the box is equal and opposite to the force exerted by the box on the floor.

    According to Newton's Third Law, the force exerted by the box on the floor (action) is equal in magnitude and opposite in direction to the force exerted by the floor on the box (reaction).

  4. Q4. If a man pushes a wall with a force of 100 N, the wall exerts an equal and opposite force on the man. What is the magnitude of the force exerted by the wall on the man?

    • A0 N
    • B200 N
    • C100 N
    • D50 N
    Show answer & explanation

    Correct answer: C — 100 N

    According to Newton's Third Law, the force exerted by the wall on the man is equal in magnitude to the force exerted by the man on the wall.

  5. Q5. In the context of Newton's Third Law, if the force exerted by a system on an external object is measured, what is the force exerted by the external object back on the system?

    • AZero force
    • BAn equal and opposite force
    • CA force dependent on mass
    • DA greater force
    Show answer & explanation

    Correct answer: B — An equal and opposite force

    The action and reaction forces are always equal and opposite. If the system exerts a force on an external object, the external object exerts an equal and opposite force back on the system.

  6. Q6. When a book is placed on a table, which statement correctly describes the action and reaction forces according to Newton’s Third Law of Motion?

    • AThe action force is exerted by the book, and the reaction force is exerted by the table on the book.
    • BThe action force and the reaction force are equal in magnitude but opposite in direction, and they act on different bodies.
    • CThe reaction force is zero because the book is at rest.
    • DThe force exerted by the book on the table is greater than the force exerted by the table on the book.
    Show answer & explanation

    Correct answer: B — The action force and the reaction force are equal in magnitude but opposite in direction, and they act on different bodies.

    Newton's Third Law states that for every action, there is an equal and opposite reaction. In this case, the book exerts a downward force (action) on the table, and the table exerts an upward force (reaction) on the book. These forces are equal in magnitude, opposite in direction, and act on different objects (book and table).

  7. Q7. When two billiard balls are colliding, the force exerted by the first ball on the second ball is equal and opposite to the force exerted by the second ball on the first ball. This illustrates which law of motion?

    • AFirst Law of Motion
    • BLaw of Conservation of Momentum
    • CThird Law of Motion
    • DSecond Law of Motion
    Show answer & explanation

    Correct answer: C — Third Law of Motion

    Newton's Third Law states that for every action, there is an equal and opposite reaction. The collision force between the two balls is an action-reaction pair, thus demonstrating the Third Law of Motion.

  8. Q8. When two objects, A and B, exert forces on each other, what is the relationship between the action force exerted by A on B and the reaction force exerted by B on A?

    • AThe action force is equal in magnitude and opposite in direction to the reaction force
    • BThe action force is greater than the reaction force
    • CThe action force is zero
    • DThe action force is half the reaction force
    Show answer & explanation

    Correct answer: A — The action force is equal in magnitude and opposite in direction to the reaction force

    According to Newton’s Third Law of Motion, the action force exerted by object A on object B is always equal in magnitude and opposite in direction to the reaction force exerted by object B on object A.

  9. Q9. When the Earth exerts a gravitational force on the Moon, what is the reaction force exerted by the Moon on the Earth according to Newton's Third Law?

    • AThe Moon exerts no force on the Earth.
    • BThe reaction force is directed towards the Sun.
    • CThe reaction force is caused only by the Moon's mass.
    • DThe Moon exerts an equal and opposite force on the Earth.
    Show answer & explanation

    Correct answer: D — The Moon exerts an equal and opposite force on the Earth.

    Newton's Third Law states that forces occur in equal and opposite pairs. If the Earth pulls the Moon, the Moon simultaneously pulls the Earth with an equal magnitude of force in the opposite direction.

  10. Q10. Consider two masses, m₁ and m₂, connected by a massless string. If m₁ pulls m₂ to the right with a force F, what is the nature of the force m₂ exerts on m₁?

    • Am₂ exerts no force on m₁.
    • Bm₂ exerts a force F to the right on m₁.
    • Cm₂ exerts a force F to the left on m₁.
    • Dm₂ exerts a force 2F on m₁.
    Show answer & explanation

    Correct answer: C — m₂ exerts a force F to the left on m₁.

    According to Newton's Third Law, the force m₂ exerts on m₁ is equal in magnitude (F) and opposite in direction (to the left) to the force m₁ exerts on m₂ (to the right).

  11. Q11. The forces described by Newton's Third Law of Motion are always:

    • AUnbalanced forces
    • BFrictional forces
    • CInternal forces
    • DExternal forces
    Show answer & explanation

    Correct answer: C — Internal forces

    Action and reaction forces are internal forces between the interacting objects.

  12. Q12. When a gun is fired, the recoil of the gun is an example of which principle of motion?

    • ANewton's Third Law of Motion.
    • BNewton's Second Law of Motion.
    • CLaw of Conservation of Momentum.
    • DNewton's First Law of Motion.
    Show answer & explanation

    Correct answer: A — Newton's Third Law of Motion.

    The recoil of the gun is due to the action-reaction pair: the force exerted by the gun on the bullet, and the equal and opposite force exerted by the bullet on the gun.

  13. Q13. The forces that cause the acceleration of an object are always an action-reaction pair. This statement is conceptually flawed because:

    • AThe sum of action and reaction forces is never zero.
    • BAcceleration is caused only by unbalanced external forces.
    • CAcceleration requires external forces acting on the body.
    • DThe action-reaction pair only exists between two interacting objects.
    Show answer & explanation

    Correct answer: D — The action-reaction pair only exists between two interacting objects.

    Acceleration is caused by the net external force (which may or may not be an action-reaction pair). Action-reaction pairs relate internal interactions, not necessarily the net external force causing acceleration.

  14. Q14. Two people are pushing against a stationary wall with the same force. What is the nature of the force exerted by the wall on the two people?

    • AThe wall exerts a force only on the person pushing harder
    • BThe wall exerts a reaction force on each person
    • CThe wall exerts a net force on the people
    • DThe wall exerts no force on the people
    Show answer & explanation

    Correct answer: B — The wall exerts a reaction force on each person

    When the two people push the wall, the wall exerts an equal and opposite reaction force back on both people. This force is the action-reaction pair involving the wall.

  15. Q15. Newton's Third Law of Motion states that for every action, there is an equal and opposite reaction. This means the action and reaction forces are always:

    • AActing on the same body
    • BOpposite in direction
    • CEqual in magnitude and opposite in direction
    • DUnequal in magnitude
    Show answer & explanation

    Correct answer: C — Equal in magnitude and opposite in direction

    The forces are equal in magnitude and act in opposite directions.

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