# Bungee Jumper

1. Nov 15, 2009

### snoitcelfer

1. The problem statement, all variables and given/known data

an 80Kg bungee jumper steps off the jump platform which is 50m above the ground.
the bungee cord is 25m long when relaxed and has an E value of 8 MPa and a cross sectional area of 400mm^2.
Calculate the closest the jumper gets to the ground. Consider the center of gravity of the jumper to be at the end of the bungee cord.

2. Relevant equations

Energy conservation / strain energy

3. The attempt at a solution

i am stuck here because facing this problem i can find solutions using energy conservation such as mgh = (1/2)k(h-L)^2. however I have no idea how to get k from this as k = fx and i am not given a length with the jumper attached. so is it possible to find k from this information or do i need to go in a different direction?

2. Nov 15, 2009

### nvn

snoitcelfer: Perhaps they want you to use the relaxed (initial) length L and assume k = E*A/L. But maybe someone will give a second opinion.

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