A 65 kg high jumper starts his push-off phase with his center of mass .45 m above groung and velocity of 0 m/s. At the end of his push-off his center of mass is .9 m above ground. The average GRF during push-off was 3000 N. He lands on a 1 m tall mat that depresses .5 m when he comes to a stop.
a. How much work did the mat do on the high jumper?
b. What is the average force the mat exerted on the high jumper?