## Mass on a Spring

A mass on a spring executes simple harmonic motion about the equilibrium point.

We can derive the equation of simple harmonic motion by applying Newton's second law of motion at a point. Suppose the spring is extended from the equilibrium point a distance x downwards. Then according to Hooke's Law the mass experiences a forceupwards:

- the minus sign indicates decreasing x.

This equation takes the form of the simple harmonic motion equation.