Question

A tennis ball of 0.2kg mass moving with a velocity of 12m/s is hit with a bat which causes it to move in a reverse direction with velocity of 18m/s.if the force of blow acted on the ball for 0.001sec, calculate the average force exerted on the ball by the batter?

Answer 1

Given,

The mass of th ball, m=0.2 kg

Let us assume that the direction in which the ball was initially moving is the negative direction.

The initial velocity of the ball u=-12 m/s

The final velocity of the ball, v=18 m/s

The interval for which the force acted on the ball, t=0.001 s

From one of the equations of the motion, we have

$v=u+at$

Where a is the acceleration of the ball during this interval.

On rearranging the above equation,

$a=\frac{v-u}{t}$

On substituting the known values in the above equation,

$\begin{gathered} a=\frac{18-(-12)}{0.001} \\ =\frac{30}{0.001} \\ =30\times10^3m/s^2 \end{gathered}$

From Newton's second law, the force on the ball is given by,

$F=ma$

On substituting the known values in the above equation,

$\begin{gathered} F=0.2\times30\times10^3 \\ =6\times10^3\text{ N} \end{gathered}$

Therefore the average force exerted by the batter on the ball is 6×10³ N