a very light rigid rod with a length of .500m extends straight out from one end of a meterstick. the meterstick is suspended from a pivot at the far end of the rod and is set into oscillation. determine the period of oscillation (hint: use the parallel-axis theorem)

Question

a very light rigid rod with a length of .500m extends straight out from one end of a meterstick.  the meterstick is suspended from a pivot at the far end of the rod and is set into oscillation.  determine the period of oscillation (hint: use the parallel-axis theorem)

i can't get the right answer...2.09 seconds

drwls · Answer

If the rigid rod is "very light" then the mass of the meter stick must also be considered. You need to calculate the moment of inertia of the meter stick + rod combination, rotating about the end of the meter stick. That is where the parallel axis theorem comes in. I tried to do the calculation of the period by ignoring the mass of the meter stick and got 2.26 s

For more about the period of such a solid pendulum, see
http://hyperphysics.phy-astr.gsu.edu/Hbase/pendp.html