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?

9.7 m/s

Explanation:

Considering the law of conservation of energy, potential energy equals kinetic energy and since

Potential energy= mgh while kinetic energy =

Then where g is acceleration due to gravity, m is mass, h is height and v is the velocity.

Taking g as 9.81 and height given as 4.8 m then

f=ma newton's second law 7x8=56n

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