Mechanical Energy: Kinetic Energy (EPE)

Question

A spring stores 77J of potential energy when it is stretched by 7cm. What is the spring constant?

Answer 1

The elastic potential energy is equal to U = 1/2·k·(Δx)² where k is the spring constant and Δx is the displacement. Solving for the spring constant k,

k = 2·U/(Δx)²

Thus,

k = 2·(77 J)/(0.07 m)² ≈ 31428.6 N/m