# Does damping of period affect the period?

1. Apr 29, 2010

### sajama

Hi there,

Sorry typo in the title and I can't figure out how to change it!
I am just wondering if anyone can help me - does damping (drag) increase the period of a pendulum? As opposed to if it was in a vacuum?

I have been trying to figure this out for some time - I know that drag is dependent on the velocity of the period, but does it actually change the period?

I am giving a presentation on how the period of a physical pendulum increases as the mass distribution changes (centre of mass lowers, the effective length gets longer) and I was once told by a lecturer that damping does not in fact change the period, but I don't see how? Surely it would slow it down, thus increasing the period?

Would greatly appreciate any thoughts on this!

:)

2. Apr 29, 2010

### Stonebridge

In general, over damping and critical damping of the system produce non-periodic motion.
Under damping will produce a frequency that is less than the natural frequency by an amount that depends on the "damping ratio".
Plenty of information here
http://en.wikipedia.org/wiki/Damping#System_behavior
For air pendulums the amount of damping is very small, resulting in a negligible decrease.

3. Apr 29, 2010