# Work / kinetic energy

• August 25th 2007, 01:47 AM
Work / kinetic energy
A baseball pitcher throws a fastball that leaves his hand at a speed of 36.0m/s. The mass of the baseball is 0.145kg. Ignore air resistance. How much work has the pitcher done on the ball in throwing it?

I dunno what to use

$W = \frac{1}{2}m{v_{2}}^2 - \frac{1}{2}m{v_{1}}^2$

the answer is 94.0 Joules
• August 25th 2007, 02:23 AM
CaptainBlack
Quote:

Originally Posted by ^_^Engineer_Adam^_^
A baseball pitcher throws a fastball that leaves his hand at a speed of 36.0m/s. The mass of the baseball is 0.145kg. Ignore air resistance. How much work has the pitcher done on the ball in throwing it?

I dunno what to use

$W = \frac{1}{2}m{v_{2}}^2 - \frac{1}{2}m{v_{1}}^2$
KE is zero (zero speed), and the final KE is $\frac{0.145\times 36^2}{2}$