View Full Version : Broken Pendulum
 
 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