If I hang a small cylindrical object with a string, I get a pendulum. When I swing it, the object mostly rotates about its axis. What effect does this rotation have on the time period of the pendulum? Can we find out the effect quantitatively?

Question

anonymous · Answer

T = 2π*SQRT(L/g)
 so i dont think that the torque would poduce any effect on the time period as T is independent of mass(moment of inertia) in casev of rotating objects

anonymous · Answer

post further questions in physics section as there are good answering people there

anonymous · Answer

Interesting question,
@Salini - That relation is only valid for point mass objects.
This is a cylinder.
Hence we have to consider it a torsional as well as physical pendulum  according to the question.
That's what you're asking right?

mani_jha · Answer

yeah, that's right siddhantsharan. i want it for a sphere or cylinder or any rigid object

mani_jha · Answer

and there will be some effect, even if little. that i am certain, because while measuring the time period of a pendulum in the lab, we were asked to make sure that the bob doesnt rotate about its axis

anonymous · Answer

Yes I think youre right.
g eff. will decrease.

anonymous · Answer

Sorry For Replying relli late.

anonymous · Answer

And Even the Amplitude will decrease.
Reason: Total Energy remains constant.

anonymous · Answer

from the experiments using a simple pendulum i have noticed that as the pendulum starts to rotate slowly,the time of oscillations starts to decrease

mani_jha · Answer

@201116252, That's probably because the amplitude decreases. The pendulum should take less time to cover less distance.