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=(v-u)/(t)`

On substituting the known values in the above equation,

`\begin{gathered} a=(18-(-12))/(0.001) \\ =(30)/(0.001) \\ =30*10^3m/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*30*10^3 \\ =6*10^3\text{ N} \end{gathered}`

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