# Problem: Your adventurous friend Lola goes bungee jumping. She leaps from a bridge that is 100 m above a river. Her bungee cord has an un-stretched length of 50 m and a spring constant k = 600 N/m. Lola has a mass of 48 kg. Lola stretches the bungee cord and it brings her to a stop. She then bounces back up again. What type(s) of energy does the system have at the instant she comes to rest at her lowest point? (i.e., gravitational PE, elastic PE, kinetic energy, etc.)

###### FREE Expert Solution

Gravitational potential energy:

$\overline{){{\mathbf{U}}}_{{\mathbf{g}}}{\mathbf{=}}{\mathbf{m}}{\mathbf{g}}{\mathbf{h}}}$

Kinetic energy:

$\overline{){\mathbf{K}}{\mathbf{E}}{\mathbf{=}}\frac{\mathbf{1}}{\mathbf{2}}{\mathbf{m}}{{\mathbf{v}}}^{{\mathbf{2}}}}$

Elastic potential energy for a stretched cord/spring:

$\overline{){{\mathbf{U}}}_{{\mathbf{e}}}{\mathbf{=}}\frac{\mathbf{1}}{\mathbf{2}}{\mathbf{k}}{{\mathbf{x}}}^{{\mathbf{2}}}}$

Lona's mass is the major source of gravitational potential energy and kinetic energy in the system. The bungee cord contributes to the elastic potential energy of the system.

At her lowest point:

Her velocity is zero. Thus the kinetic energy is zero.

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###### Problem Details

Your adventurous friend Lola goes bungee jumping. She leaps from a bridge that is 100 m above a river. Her bungee cord has an un-stretched length of 50 m and a spring constant k = 600 N/m. Lola has a mass of 48 kg.

Lola stretches the bungee cord and it brings her to a stop. She then bounces back up again.

What type(s) of energy does the system have at the instant she comes to rest at her lowest point? (i.e., gravitational PE, elastic PE, kinetic energy, etc.)

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Equations for Energy Conservation concept. If you need more Equations for Energy Conservation practice, you can also practice Equations for Energy Conservation practice problems.