1. What is the gravitational energy (relative to the unstretched surface of the trampoline) of the 20 kg ball at its apex 2 m above a trampoline?

1.  What is the gravitational energy (relative to the unstretched surface of the trampoline) of the 20 kg ball at its apex 2 m above a trampoline?

2.  What is the kinetic energy of the ball just before impacting the trampoline?

3.  At maximum stretch at the bottom of the motion, what is the sum of the elastic and gravitational energy of the ball?