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 7.0-kg box slides along a frictionless floor at 1.7 m/s. The box collides with a spring of negligible mass that compresses by 23 cm before the box comes to a halt.
How much kinetic energy does the box have before it collides with the spring?
Calculate the work done by the spring.
Determine the spring constant of the spring.