Question

 A baseball bat with 100. J of energy strikes a ball with a mass of 150. g. The energy transfer is only 20.0 % efficient. Calculate the initial speed of the ball.

Answer 1

$A = Q+E_k$

$E_k = \frac{20*A}{100}=20\text{ J}$

$E_k=\frac{mV^2}{2};\ V=\sqrt{\frac{E_k*2}{m}}=\sqrt{\frac{20*2}{0.150}}= \approx16.33\ \frac{m}{s}$

Answer:$V= \approx16.33\ \frac{m}{s}$