Conor can throw a 360 g ball with a speed of 34 m/s. He moves his hand forward 1.1 m while doing so. (a) How much work does Conor do on the ball? (b) How much force, assumed to be constant, does Conor apply to the ball? (c) What is Conor's maximum power output as he throws the rock?

Solution:

Given,

m = 0.36 kg

v = 34 m/s

d = 1.1 m 

a) Work is change in energy. Assuming zero kinetic energy to start with and neglecting any change in potential energy (no upward movement), work done is equal to resulting kinetic energy

$E_{kin}$ = $\frac{1}{2}mv^2$ = $\frac{1}{2}$ 0.36 kg  (34 m/s)^2 = 208.08 J

b) Work = F * d (Force applied times distance moved in direction of applied force)

=> 208.08 = F (1.1) => F = $\frac{208.08}{1.1}$ = 189 N

c) Power = F * v, since F is considered constant, max power is at max v (34m/s)

Power = 189 N * 34 m/s = 6431.6 W = 6.43 kW