SSC Selection Post 2025 PYQ — Question 13

Correct Answer

For every action, there is an equal and opposite reaction

Explanation

Newton's Third Law of Motion states that forces in nature never exist in isolation; they always exist in pairs. When one object exerts a force on a second object, the second object simultaneously exerts an equal force in the opposite direction on the first. This is commonly referred to as "action" and "reaction."

Key Points

This law clarifies that the forces of "action" and "reaction" always act on two different objects; therefore, they never cancel each other out.

For example, when you jump from a boat onto the shore, you push the boat backward (action), and the boat pushes you forward (reaction).

The launch of a rocket is also a perfect example of this law, where the gases produced by burning fuel exert a downward force, and the rocket receives upward motion (reaction) in return.

Additional Facts

Newton's First Law deals with Inertia, while the Second Law defines the relationship between force, mass, and acceleration ($F = ma$).

The Third Law is also the foundation of the Law of Conservation of Momentum.

Important Questions

Question: How does Newton's Third Law work in Rocket Science?

Answer: A rocket expels gases backward at high speed (action), which results in the rocket receiving an equal and opposite force (reaction) to move forward.

Question: Do action and reaction forces always balance each other out?

Answer: No, because they always act on two different objects.