# Homework Help: The Pendulum

1. Mar 29, 2010

### roam

1. The problem statement, all variables and given/known data

Imagine a pendulum which consists of a particle like bob of mass m suspended by a massless string of length L. Using the following equation

$$T=2 \pi \sqrt{\frac{L}{g}}$$

given the mass of the bob is 100 g, what is the length of the pendulum supposed to be if we want its period to be 2 seconds?

3. The attempt at a solution

So do I need to substitute g=9.81 or do I need to use the mass to find a new value for g? Is the follwoing correct:

$$2=2 \pi \sqrt{\frac{L}{9.81}}$$

$$L=1$$

I didn't even need to use m=100! Then why did they give us the value for mass if it was useless? am I missing something?

2. Mar 29, 2010

### rl.bhat

The period of the simple pendulum is independent of the mass of the bob.

3. Mar 29, 2010