## Physics for Scientists and Engineers: A Strategic Approach with Modern Physics (3rd Edition)

The work done by the sprinter is equal to the kinetic energy at 3.0 s. We can find the work $W_s$ done by the sprinter. $W_s = KE$ $W_s = \frac{1}{2}mv^2$ $W_s = \frac{1}{2}(70~kg)(10~m/s)^2$ $W_s = 3500~J$ We can find the sprinter's average power output; $P_{ave} = \frac{W_s}{t}$ $P_{ave} = \frac{3500~J}{3.0~s}$ $P_{ave} = 1170~watts$ The sprinter's average power output is 1170 watts. The work done by the greyhound is equal to the kinetic energy at 3.0 s. We can find the work $W_{gh}$ done by the greyhound. $W_{gh} = KE$ $W_{gh} = \frac{1}{2}mv^2$ $W_{gh} = \frac{1}{2}(30~kg)(20~m/s)^2$ $W_{gh} = 6000~J$ We can find the greyhound's average power output. $P_{ave} = \frac{W_{gh}}{t}$ $P_{ave} = \frac{6000~J}{3.0~s}$ $P_{ave} = 2000~watts$ The greyhound's average power output is 2000 watts.