# Homework Help: Pendulum and Gravity

1. Nov 19, 2005

### Effitol840

Alright so here’s the problem. In lab we are supposed to come up with a way to figure out gravity using an experiment. The experiment that I came up with is to use a pendulum and find its period and then calculate the gravity. I know this is possible but I don’t know the equations. If anyone can help me out with the equations for this type of problem it would be much appreciated. Also, would it be better to do a few different string lengths or keep the string length constant?

2. Nov 19, 2005

### Janus

Staff Emeritus
The period of a simple pendulum is

$$T=\pi \sqrt{ \frac{L}{g}}$$

With L being the length of the pendulum.

I would use the longest string you possibly can.

3. Nov 19, 2005

### Fermat

Remember, that expression,

$$T=\pi \sqrt{ \frac{L}{g}}$$

is an approximation and is accurate only for small oscillations, where $$sin\theta \approx \theta$$

That's why you should use as long a string as possible, so as to keep the amplitude of oscillation as small as possible.

4. Nov 19, 2005

### Effitol840

Thanks... I need to run the expirement again. If I have any more questions I'll be sure to ask.