Question

Sam hits a baseball of mass 200 g from his bat and scores a homerun. The speed of the ball changed from 10 ms${}^{-1}$ to 20 ms${}^{-1}$ after hitting in just 0.5 seconds. Calculate the Power delivered by the bat.

Answer 1

Given : Mass of ball = 200 g = 0.2 kg, Initial speed of the ball = 10 ms${}^{-1}$, Final speed of the ball = 20 ms${}^{-1}$, Time interval = 0.5 seconds

Using work-energy theorem for the ball,
1/2 mv${}^2$ - 1/2 mu${}^2$ = Work done on the ball by the bat
=>1/2 m (v${}^2$ - u${}^2$) = W
=> 1/2 x 0.2 x ( (20)${}^2$ - (10${}^2$) ) = W
=> W = 30 J

Now, Power = Work done / time interval
=> P = 30 / 0.5
=> P = 60 Watt