Bungee Jump

[physicsss]

A bungee jumper with mass 200.0 kg jumps from a high bridge. After reaching his lowest point, he oscillates up and down, hitting a low point eight more times in 30 s. He finally comes to rest 20.0 m below the level of the bridge. Calculate the spring constant of the bungee cord and the unstretched length of the bungee cord.

How do I approach this problem?

[aviv87]

Well, you know that T = 30/8 = 3.75
And T=2\cdot\pi\cdot\sqrt{\frac{m}{k}} => k = 561.47[N/m]
You also know that 20m under the bridge a=0
\Sigma \vec{F} = 0
mg=k\Delta L
Now you just need to get \Delta L.

HTH