A cricket player catches a ball of mass 120 g moving with 25 m / s speed. If the catching process is completed in 0.1 s then the magnitude of force exerted by the ball on the hand of player will be (in SI unit) :

Solution

Physics sir · 3 steps

The ball's whole momentum is taken away in 0.1 s, so force is that momentum divided by the time.

1. Change in momentum. Convert the mass first: 120 g = 0.12 kg. The ball comes to rest, so its momentum drops from 0.12 × 25 = 3 kg m s⁻¹ to zero. The change has magnitude 3 kg m s⁻¹.
2. Impulse equals change. The impulse from the hand equals this change in momentum. The average force is the change in momentum divided by the time it takes.

   F = (Δ p)/(Δ t) = (0.12 × 25)/0.1 = 3/0.1 = 30 N

3. So. By Newton's third law, the ball pushes on the hand with the same 30 N that the hand exerts on the ball. The answer is (a).

The idea to keep. Average force is change in momentum divided by contact time. Change grams to kilograms before you multiply, and remember the force on the hand equals the force on the ball.

Answer from the NTA final answer key. Solution by PrepWiser.