Elastic Potential Energy Physics Example 3

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Example 3

medium
A bungee cord (k=50 N/mk = 50 \text{ N/m}) stretches 4 m4 \text{ m} beyond its natural length when a jumper reaches the lowest point. How much elastic PE is stored?

Solution

  1. 1
    Use PE=12kx2PE = \frac{1}{2}kx^2.
  2. 2
    PE=12(50)(4)2=12(50)(16)=400 JPE = \frac{1}{2}(50)(4)^2 = \frac{1}{2}(50)(16) = 400 \text{ J}

Answer

PEelastic=400 JPE_{\text{elastic}} = 400 \text{ J}
At the lowest point of a bungee jump, all the gravitational PE lost has been converted to elastic PE in the stretched cord. The large stretch compensates for the relatively small spring constant.

About Elastic Potential Energy

Energy stored in an elastic object that has been stretched or compressed from its natural length.

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