Solve Energy Stored Problem: 70kg Man, 85m Fall, 50m Bungee

[Rampage]

Im really stuck with this question, hoping someone could give me a hand

A bungee rope of unstretched length 50M is designed to allow a 70Kg man to come to rest 85m below the platform from which he jumps.

Calculate the energy stored in the rope when the man has come to rest. Ignore the weight of the rope.
(Gravitational field strength 9.8)


Calculate the gravitational potential energy lost by the man when he comes to rest.


Am i right to do
70 x 9.8 = 686N
Work Done = Force x Displacement
=24.1Kj?

Im not sure if I am using the correct formula, and I am totally stuck on the 2nd part

 

[pervect]

Am i right to do
70 x 9.8 = 686N

Yes, that's right so far

Work Done = Force x Displacement
=24.1Kj?

The displacement is wrong

Im not sure if I am using the correct formula, and I am totally stuck on the 2nd part

The second part is the key to the problem.

Try reading

http://id.mind.net/~zona/mstm/physics/mechanics/energy/gravitationalPotentialEnergy/gravitationalPotentialEnergy.html