Ignoring details associated with friction, extra forces exerted by arm and leg muscles, and other factors, we can consider a pole vault as the conversion of an athlete’s running kinetic energy to gravitational potential energy. If an athlete is to lift his body 4.8 m during a vault, what speed must he have when he plants his pole?
A sprinter of mass 60 kg accelerates from 2.00 m/s to 8.00 m/s over a 25.0-m-distance of racetrack. The sprinter is running into the wind, which exerts an average force of 30.0 N. What average force does the sprinter exert on the track?
A sled of mass 70 kg starts from rest and slides down a incline 80 m long. It then travels for 20 m horizontally before starting back up an incline. It travels 80 m along this incline before coming to rest. What is the net work done on the sled by friction?