we've been studying te physics involved in bungee jumping. We went to a bungee site, and recorded data, such as length of rope, weight of jumper, distance to fall, etc. With the data we collected, I've been able to determine spring constant, equilibrium point, force exerted etc. But I've been having trouble to work out the height the jumper will bounce back up to after reaching the lowest point. Here's an example: k= 50 N/m x= 50 m (this includes the length of cord) length of cord= 10m so f=k(x-L) =50 x 40 = 2000 N and that his elastic potential energy at the bottom = E grav potential at top m= 80kg mgx=.5k(x-L)^2 Eep=40000 J But using this how do i find the height the jumper will bounce to? I'm pretty sure he wouldn't reach the same height he fell from, due to gravity.