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yahoo4
Jul 24, 2009, 07:41 PM
Hello

I am interested in finding out the equation for the period of the broken pendulum. This is a simple pendulum which hits a rod that breaks its swing directly beneath the equilibrium point.

kiwiminstp
Aug 1, 2010, 07:42 PM
T = pi * sqrt(B/g) + pi * sqrt(L/g) where B is the short length, L is the full length assuming half the swing is at the full length and half at the shorter length

Corneil
Jun 29, 2011, 12:05 AM
Hey. Could you by any chance explain why that is? In physics terms?

kiwiminstp
Jun 29, 2011, 12:26 AM
Yes I can!

The "normal" period of a pendulum is
T = 2\pi \sqrt{\frac{l}{g}}

"Half a swing" would be
\pi \sqrt{\frac{l}{g}}

So the period of a broken pendulum would be
\pi\sqrt{\frac{l_{long}}{g}} + \pi \sqrt{\frac{l_{short}}{g}}

How hard is that?

kittykat12
May 23, 2012, 12:46 AM
Can anyone help on the physics theory of the broken pendulum?

ebaines
May 23, 2012, 11:30 AM
Can anyone help on the physics theory of the broken pendulum?

What do you want to know? The previous post did a good job of explaining why the period is what it is, but it assumes you know that the period for a simple pendulum is 2 \pi \sqrt{\frac L g } . If you would like to know why that is - it requires solving the differential equation for a pendulum's motion, which you can get by drawing the free body diagram and considering that F=ma. If you want to see more about how to do this - see:

http://www.physicsclassroom.com/class/waves/u10l0c.cfm