# Harmonic motion

1. Mar 13, 2005

### Rave Grrl

Can someone explain this:

For question A I originally got around .142 M, but that was apparently wrong, because I assumed the phase constant was zero. Can someone explain what the phase constant is and how to find it?

A simple harmonic oscillator consists of a block of mass 2.60 kg attached to a spring of spring constant 180 N/m. When t = 3.00 s, the position and velocity of the block are x = 0.129 m and v = 3.415 m/s.
(a) What is the amplitude of the oscillations?

(b) What was the position of the mass at t = 0 s?

(c) What was the velocity of the mass at t = 0 s?

2. Mar 13, 2005

### Sirus

Here's a link for phase constant.

Use energy concepts to solve this problem. Remember that mechanical energy is conserved, so the sum of the kinetic and elastic potential energies of the mass is constant throughout its movement. Energy gradually transfers between the two types as the mass moves. Here are some useful formulae:

$$E_{\mbox{k}}=\frac{1}{2}mv^{2}$$

$$E_{\mbox{elastic potential}}=\frac{1}{2}kx^{2}$$

where k is the spring constant and x is the distance from equilibrium of the mass.