Question

A 890N BUNGEE JUMPER JUMPS FROM A BRIDGE 39.6M ABOVE THE RIVER. THE BUNGEE CORD HAS AN UNSTRETCHED LENGTH OF 18.3M AND HAS A SPRING CONSTANT K=204N/M. (A) HOW FAR ABOVE THE RIVER IS THE JUMPER WHEN THE CORD BRINGS HIM TO A STOP?

Answer 1

I think this needs a little modification:

The body loses the PE as it falls 18.3m

HOWEVER - it loses MORE PE as the cord stretches - so the total distance fallen = 18.3 + stretch total PE loss = mg(18.3+x) (x is stretch)


the energy stored in the cord at max stretch is 0.5kx^2 (x is stretch)

so:
mg(18.3+x) = 0.5kx^2