Question

1. A cricket ball of mass 150 g is moving with a
velocity of 12 ms-7, and is hit by a bat, so that the
ball is turned back with a velocity of 20 ms-7. The
force of the blow acts for 0.01 second on the ball.
Find the average force exerted by the bat on the
ball. [Central Schools 04, 05, 07] (Ans. 480 N)​

Answer 1

Correct Question

• A cricket ball of mass 150 g is moving with a velocity of 12 ms⁻¹ and is hit by a bat so that the ball is turned back with a velocity of 20 ms⁻¹. The force of the blow acts for 0.01 second on the ball. Find that force?

Given

• Mass of the ball = 150 g
• Velocity = 12 m/s
• The ball is hit by a bat and the ball returns with a velocity of 20 m/s
• The force of the blow acts for 0.01 second on the ball

To Find

• Average force exerted by the bat

Solution

☯ Here we shall use the formula : Change in Momentum = F × t = Impulse

☯ First Change the Mass from g → Kg. Then find the initial and the final momentum which gives us the change in Momentum as we subtract the two. Substituting these in the formula will give us our answer

Converting Mass of the Body

→ 1 kg = 1000 g

→ 150 g = 150/1000

→ Mass = 0.15 kg

★ Change in Momentum

→ Change in Momentum = mv - mu

→ Change in Momentum = m(v-u)

→ Change in Momentum = 0.15(12-[-20])

→ Change in Momentum = 0.15(12+20)

→ Change in Momentum = 0.15(32)

→ Change in Momentum = 4.8

━━━━━━━━━━━━━━━━━━━━━

✭ Average Force

→ F × 0.01 = 4.8

→ F = 4.8/0.01

→ F = 480 N

Answer 2

Explanation:

Given :

• A cricket ball of mass 150 g is moving with a velocity of 12 ms-1, and is hit by a bat.

• the ball is turned back with a velocity of 20 ms-1,

• The force of the blow acts for 0.01 second on the ball.

To Find :

• Find the average force exerted by the bat on the ball.

Solution :

Concept :

• A change in speed, or a change in direction, or a change in both speed and direction means that the object has a change in velocity.

• * Understand that in physics this means if you turn a corner, even if your speed is constant, your velocity changes. Often the velocity of an object is not constant.

_________________________

Change in velocity = Final - intial velocity

Substitute all Values :

Change in velocity = 20 - (-12) = 32 m/s

Force = mass × change in velocity / time

Substitute all Values :

Force = 150 x 32 / 0.01

Force = 15 x 32 = 480 N

• Average force on the ball is 480 N