# Homework Help: Angular Momentum Part II

1. Nov 2, 2004

### rykirk

Hey guys,

I was wondering if you could give me some guidance on this problem...

Two lightweight rods 20 cm in length are mounted perpendicular to an axle and at 180 degrees to each other. At the end of each rod, there is a 600 g mass. The rods are spaced 40 cm apart along the axle. The axle rotates at 30 rad/s, what is the component of the total angular momentum along the axle?

Thanks for all the help yesterday guys in my previous post. I was able to calculate the correct angular momentum which was 1.92 kg x m^2/s

I'm now stumped on the next part of the question which says:

What angle does the vector anguler momentum make with the axle. My professor gave me the hing that the vector angular momentum must be calculated about the same point for both masses.

Any Suggestions?

Thanks,

Ryan

2. Nov 3, 2004

### Staff: Mentor

In general, the angular momentum of a body is not parallel to its axis of rotation. Find the total angular momentum by adding the angular momentum of each mass, which is given by $\vec{L} = \vec{r}\times \vec{p}$, using the same point as an origin. (I'd use the center of mass.)