Finding the unstretched length of a bungee cable

Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
1 reply · 4K views
jbrizown
Messages
2
Reaction score
0
Two men both weighing 150lb jump off a bridge using a bungee cord with stiffness k=80lb/ft. One of the men is attached to the cable and plans to release the other man when they reach the water 120ft below the bridge. Once there the connected man will let go of the unconnected man when they touch the water. Determine the unstretched length of the cord. Also determine the maximum acceleration of the attached man and the maximum height he reaches above the water when he springs back up.



Homework Equations


T1 + ƩU = T2

Us = 1/2 k (s)^2


The Attempt at a Solution



I used mgh for U and got an unstretched length of 90ft, but I'm not sure if it's correct and I don't know how to approach the kinematics of the second portion.
 
Physics news on Phys.org