Inertia and Momentum Question

[shell4987]

Homework Statement

Figure 11-45 shows a rigid structure consisting of a circular hoop of radius R and mass m, and a square made of four thin bars, each of length R and mass m. The rigid structure rotates at a constant speed about a vertical axis, with a period of rotation of 2.8 s. Assuming R = 0.62 m and m = 1.2 kg, calculate (a) the structure's rotational inertia about the axis of rotation and (b) its angular momentum about that axis.

Homework Equations

I already solved part (a) but the equations to use for part (b) are L=Iw

The Attempt at a Solution

I put in the I that I received from part (a) which is 1.5, however I don't know how to find angular velocity... Can anyone help me out?

 

[hage567]

however I don't know how to find angular velocity... Can anyone help me out?

You figure it out from this:

The rigid structure rotates at a constant speed about a vertical axis, with a period of rotation of 2.8 s.

 

[ogb p]

To find the angular velocity, you can use the equation ω = 2π/T, where T is the period of rotation. In this case, T = 2.8 s, so ω = 2π/2.8 s = 2.24 rad/s. Once you have the angular velocity, you can plug it into the equation L = Iω to solve for the angular momentum.