Question

A spring with a spring constant value of 2500 StartFraction N over m EndFraction is compressed 32 cm. A 1.5-kg rock is placed on top of it, then the spring is released. Approximately how high will the rock rise?

9 m
17 m
27 m
85 m

Answer 1

Spring energy: U = 1/2 k x^2 = 0.5(2500)(0.32^2) = 1250(0.1024) = 128 J.

Set U = mgh => h = U/(mg) = 128/(1.5·9.8) ≈ 128/14.7 ≈ 8.7 m ≈ 9 m.

Answer: 9 m.