Calculating Closest Bungee Jump Distance

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To calculate the closest distance a bungee jumper reaches to the ground, the jumper's mass, bungee cord length, and material properties are essential. The jumper weighs 80 kg and steps off from a height of 50 m, with the bungee cord measuring 25 m when relaxed. The problem involves using energy conservation principles, specifically the equation mgh = (1/2)k(h-L)^2, but the spring constant k needs to be determined. A suggestion is made to calculate k using the formula k = E*A/L, where E is the modulus of elasticity, A is the cross-sectional area, and L is the relaxed length of the cord. Clarification on whether this approach is valid is sought, indicating a need for further discussion on the method.
snoitcelfer
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Homework Statement



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.

Homework Equations



Energy conservation / strain energy

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?
 
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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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