# Homework Help: ?'s about simple harmonic

1. Oct 25, 2004

### buffgilville

Are all periodic motions simple harmonic? Why or why not? What is an example of a periodic motion that is not simple harmonic?

2. Oct 25, 2004

### arildno

1. No; there's a lot of periodic motion which is not simple harmonics.
For example:
A swinging pendulum is not a simple harmonic oscillator.
The earth's motion around the sun is periodic, but not that of a simple harmonic..

3. Oct 25, 2004

### Tom Mattson

Staff Emeritus
A simple harmonic motion function has only a single frequency, as follows:

x1(t)=Asin(&omega;t)

Question: What happens when you add the following 2 harmonics together?

x(t)=x1(t)+x2(t)=Asin(&omega;t)+Asin(2&omega;t)

What is the period of this motion? What does the graph of x vs t look like?

The answers to those questions should get you started.

4. Oct 25, 2004

### arildno

Just to state what is ordinarily meant by a PERIODIC function:
We say that a function f is periodic in t with period T, if it exists a constant T so that
f(t)=f(t+T) (for all choices of t)