Question

Newton’s third law of motion states that for every action, there is an equal and opposite reaction. Which of the following statements can be inferred from the above-mentioned law of motion?
Statement 1: For every interaction, there is a pair of forces acting on the two interacting objects.
Statement 2: The magnitude of the force on the first object equals the magnitude of the force on the second object.
Statement 3: Forces always come in pairs - equal and opposite action-reaction force pairs.
Statement 4: Action and its reaction act on the same bodies.
Statement 5: Action and its reaction act on two different bodies.

• A. All statements can be inferred from $3^{rd}$ law of motion
• B. All statements except 5 can be inferred from $3^{rd}$ law of motion
• C. All statements except 4 can be inferred from $3^{rd}$ law of motion
• D. Only statement 1 can be inferred from $3^{rd}$ law of motion

Answer 1

The correct option is C All statements except 4 can be inferred from $3^{rd}$ law of motion

For every action, there is an equal and opposite reaction. This is Newton's third law of motion. Let's see this in detail.

• In every interaction, there is a pair of forces acting on the two interacting objects. Hence, statement 1 is correct.
• The magnitude of the force on the first object equals the magnitude of the force on the second object. Hence, statement 2 is correct.
• The direction of the force on the first object is opposite to the direction of the force on the second object. Using this and statement 2, we can conclude that statement 3 is correct.
• Action and reaction forces always come in pairs and action-reaction forces act on two different bodies. So, statement 4 is incorrect but statement 5 is correct.