Physics Final Exam: What's the force the floor exerts on a jumping human?

A human with a mass of 80 kg jumps straight up. At the beginning of the jump, the human’s center of mass is 0.55 meters above the ground. Right when the human leaves the ground, the center of mass is 0.66 meters above the ground. After leaving the ground, the human’s center of mass reaches a height of 1.1 meters above the ground. What is the average force the floor exerts on the human during the jump? What is the decrease in internal energy for the human for this jump?

[ryanJ]

Why is it that for a PPS that you assume only Kinetic work is done. Shouldn't you also include potential work like you do for the second part of the question. As in make Wg + Wf = K + P? with P = mgh

[anindya]

that should be 1920 right? mine's comes out to be

[mr.alkenly]

I just wanted to know how much force superman needs to exert to fly like that