# Find period of pendulum

1. Oct 17, 2011

### lphalo

if if we have a string and a object with mass m connected to it , it does extend for 11 cm (string) . if we put another object with the same mass m , what will be the period of that ( of the 2 objects in the string) . please explain does mass affect the period ?
thnx

2. Oct 17, 2011

### LawrenceC

Hint: Can you derive the formula for the period of a simple pendulum? Draw a free body diagram of a weight on a string not quite in the vertical position. Write the equation of motion. What can you conclude from the equation you derive?

3. Oct 17, 2011

### lphalo

i cannot derive , cause we didnt learn it , in one conclusion that i made it 'is 2 times more than the first' but i do not have a idea if its true and even if its true is my equation right :S

4. Oct 17, 2011

### lphalo

wait , even if we didnt learn this part i saw that for a string the T is 2pi square root of l /square root of g , it doesnt affect,, hmm but what must i do to find the period , i only have the increased'' length of 11cm and not the actual length before that

5. Oct 17, 2011

### LawrenceC

Is the string elastic and stretches? I'm not sure I gather that from the problem statement.