Period of Small Amplitude Oscillation for Hoop of Radius 50cm

[yus310]

Homework Statement

"A circular hoop of radiusm 50 cm is hung on a narrow horizontal rod and allowed to swing in the plane of the hoop. What is the period of its oscillation, assuming that the amplitude is small?

Homework Equations

T= 2*pi(I/(MgD))^.5

The Attempt at a Solution

Ok... so if M is not given for the hoop and the rod, how do I go about figured it out? What is the value of D? And do I factor the moment of inertia for both the rod and hoop, and if so... how do I figure out the length of the rod, if it is not given.

Thanks.

 

[robb_]

Find the moment of inertia- it will have a factor of M in it.
I believe D is the distance from the center of mass to the pivot point.
Is the rod rotating?

 

[yus310]

Find the moment of inertia- it will have a factor of M in it.
I believe D is the distance from the center of mass to the pivot point.
Is the rod rotating?

Yes.. it is swinging from the hoop