# Conservation of mechanical energy of bungee jumper

1. Oct 12, 2004

### joej

A 60kg bungee jumper jumps from a bridge. He is tied to a 12m-long bungee cord and falls a total of 31m
a) calculate the spring constant of the bungee cord
b) calculate the maximum acceleration experienced by the jumper

okay I'm stuck on b) I got a0 calculated without any problems at all, it will be 101N/m the problem with b) is that I initially thought.... how would it be possible to have an acceleration of more then 9.8m/s^2 while falling.... it isn't! but I never took into consideration the acceleration while going back up and now whatever I do I alwasy come back to the 9.8m/s^2 answer, I need someon to point me in the right direction so I can get off of this damn idea of 9.8m/s^2

2. Oct 12, 2004

### arildno

When the cord is stretched maximally, you will experience maximal upwards acceleration.
The upwards acceleration is found by subtracting mg (downwards force) from the "spring force" at maximal stretch; and then divide by "m", the mass of the jumper.
Compare then that value of maximal upwards acceleration with 9.8 (maximal downwards acceleration)