Simple Power calculation?

Question

Calculate the power you develop when you throw a 355g softball at 20m/s to first base in 1.2s?

Please show steps - the answer is 55.8W

Thanks :)

Answer 1

P=w/t=F*S/t=mgs/t=mgh/t

p=?,m=355g/1000=0.355Kg,v=20m/s,t=1.2s...

To get h we use v^2=u^2+2ah   20^2=0^2+2*10*h  400=20h h=20m

P=(0.355*10*20)/1.2   P=71/1.2=59.17w  P=59.17watt

Answer 2

I also got the same answer as yours & I could not find any kind of mistake in it.

Answer 3

The energy is easy to calculate, but to calculate the power you exhert, you need to know the time it takes you to throw the ball. The flight time has nothing to do with the problem.

But perhaps I misread the question, and the 1.2 seconds is not the flight time, but the time it takes you to swing your arm in the act of throwing the ball.

Kinetic Energy

KE = ½mV² = ½(0.355)(20)² = 71 J

Now you can get 59 watts by dividing 71 Joules by 1.2s.

.

Answer 4

I found the answer as 59.17 Watt every time. But let's look at it by this view;

P = W/t = W/1.2 =55.8

so W=66.96 = 0.5 * m * v ^ 2

then from that we found the velocity as 19.42 m/s .

it means that 0.58 m/s makes a huge difference for this question.