Question

A 1.5kg block is held in place and compresses a 150N/m spring by 30cm from its relaxed position. The block is then released. What speed will the block have at the instant when the spring is no longer compressed?

Answer 1

Answer: simple harmonic motion

Simple harmonic motion. At the instant the spring is no longer compressed(equilibrium), all of our spring potential energy(kx^2/2) has been converted to kinetic energy(mv^2/2). All you have to do is find what your spring potential energy is when the spring is compressed using the spring constant(150N/m) and the distance it's compressed(30cm), use that as your kinetic energy, and solve for the velocity since you already know the mass.