# Calculating the moment of inertia for this configuration

1. Mar 10, 2012

### Demon117

1. The problem statement, all variables and given/known data
I need to find the rotational kinetic energy of this system in the figure I have provided. Here the spring is rotating with the system at angular speed $\omega$. The two beads on the wire move vertically, and the third bead is held by two massless rods of equal length L.

3. The attempt at a solution
Would the moment of inertia for the the whole thing just be

$I_{1,3}=2mL^{2}$

$I_{2,3}=2mL^{2}$

$I_{total}=4mL^{2}$

#### Attached Files:

File size:
6.2 KB
Views:
116
Last edited: Mar 10, 2012
2. Mar 10, 2012

### SammyS

Staff Emeritus

It looks as though the system is constrained to rotate about the z-axis.

You need to find the moment of inertia about the z-axis.

3. Mar 10, 2012

### Demon117

Will it depend on the angle $\alpha$?

4. Mar 10, 2012

### SammyS

Staff Emeritus
Yes it will depend on α .