Question

What is the gravitational energy (relative to the unstretched surface of the trampoline) of the 20 kg ball at its apex 2 m above the trampoline?
b) What is the kinetic energy of the ball just before impacting the trampoline?
c) At maximum stretch at the bottom of the motion, what is the sum of the elastic and gravitational energy of the ball?
d) What conclusions can you draw from the answers found above?
I know a) Eg=400J and b) Ek=400J
I am stuck in C and d. someone help please!

Answer 1

c. At the bottom, the velocity is zero and the stretched membrane potential energy should equal what you calculate from m g h', the total change in gravitational potential energy.

d. conservation of energy is concluded?

Answer 2

I still don't get c. what formula should I use?

Answer 3

would c) be 600J ?

Answer 4

The gravitational potential energy would now be wholly converted to elastic potential energy. Unfortunately, we do not know how much the stretch is, which would add to the change in gravitational potential. How far did it stretch? Add that to mgh=400J
to get total change in gravitational PE = elastic PE..

Answer 5

so is there no numerical answer to c? I'm stuck as well. lol