- #1
whitetiger
- 22
- 0
Homework Statement
http://img120.imageshack.us/img120/808/periodicemotionhd3.jpg solid, uniform disk of mass M and radius a may be rotated about any axis parallel to the disk axis, at variable distances from the center of the disk
If you use this disk as a pendulum bob, what is T(d), the period of the pendulum, if the axis is a distance d from the center of mass of the disk?
and
The period of the pendulum has an extremum (a local maximum or a local minimum) for some value of d between zero and infinity. Is it a local maximum or a local minimum?
Homework Equations
From the picture, I come up with the moment of inertia of the solid disk around its center of mass
I = 1/2Ma^2
From the question, we are asked to find the period of the pendulum if the axis distance d from the center of mass.
The period T for this is P= 2pi (sqrt L/g) where g is the gravitation force
and L is the lenght.
From my understanding is that because of the new lenght, we need to use the Parallel Theorem to find the new lenght
I am not sure about this, so hope someone can help
Iend = Icm + Md^2
Iend = 1/2Ma^2 + Md^2
So the period is P = 2pi (sqrt(( a^2 +d^2)/g))
But this is not correct.
Thank
Last edited by a moderator: