Question

A 80 kg bungee jumper is on a bridge that is 100 meters above a river. Attached to the jumper is a bungee cord that is 50 meters long. After jumping off of the bridge, the jumper reaches a position that is 10 meters above the river when the bungee cord is at its maximum stretch.

Required:
a. How much energy is stored in the bungee cord at that maximum stretch?
b. What is the spring force constant of the bungee cord?

Answer 1

a) 70,560 J

b) 88.2 N/m

Step-by-step explanation:

The spring potential will equal the change in gravity potential

PS = PE = mgh = 80(9.8)(100 - 10) = 70,560 J

PS = ½kx²

k = 2PS/x² = 2(70560)/(100 - 50 - 10)² = 88.2 N/m