Problem 77.

Calculate the hang time of an athlete who jumps a vertical distance of .9 meters considering the acceleration of gravity is

Solution:

Without air resistance we have free fall motion. Then the maximum height can be related to the traveled distance (from the ground to the maximum height) by the equation:

where is the initial velocity.

At the maximum height the velocity is 0. Then

Then

And

The total hang time is the twice of this time: 2*0.42=0.84 s.