The propulsion of a rocket.
Explanation
Newton's Third Law of Motion states that "to every action, there is always an equal and opposite reaction." This implies that forces always occur in pairs and act on two different bodies simultaneously.- Dust particles falling off a beaten carpet. is incorrect: This phenomenon demonstrates Newton's First Law of Motion (specifically, the Inertia of Rest). When the carpet is beaten, the fabric moves suddenly, but the dust particles tend to remain at rest due to inertia and separate from the carpet.
- A fielder pulling his hands back while catching a ball. is incorrect: This is an application of Newton's Second Law of Motion (Impulse-Momentum Theorem). By pulling his hands back, the fielder increases the time duration over which the ball's momentum changes to zero. This reduces the rate of change of momentum, thereby decreasing the force of impact on the hands.
- The propulsion of a rocket. is correct: Rocket propulsion is a direct application of Newton's Third Law of Motion. The rocket engine expels hot gases backward at high speed (Action). In response, the gases exert an equal and opposite force on the rocket, pushing it forward (Reaction).
- A passenger falling forward when a bus stops suddenly. is incorrect: This is an example of Newton's First Law of Motion (Inertia of Motion). When a bus stops suddenly, the passenger's feet come to rest along with the floor of the bus, but the upper body continues to move forward due to inertia.
Key Takeaway: Newton's Third Law explains phenomena where a force exerted by one object results in a reactive force from another, such as in rocket propulsion, recoil of a gun, or swimming.