angular momentum

S

soccerball3211

Junior Member
Joined
May 16, 2005
Messages
84
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 8.4 s. Assuming R = 1.4 m and m = 2.2 kg, calculate (a) the structure's rotational inertia about the axis of rotation and (b) its angular momentum about that axis.

I was able to find the angular velocity but can someone help me find the moment of inertia?

Thanks again
 
soccerball3211 said:
the four thin bars are on one side of the axis and the hoop is on the other side of the axis
Click to expand...

well ... that statement made it clear as mud.

it might help if you use a coordinate system to describe the arrangement.

let the z-axis be the axis of rotation. from your description, it sounds like the ring and square both lie in the x-y plane, but where? is the circle tangent to the z-axis? is the square tangent to the z-axis at a corner or on a side? get my point?

if you can't provide an adequate description, then you might have to upload a sketch.
 
Sorry Skeeter,

The circle is tanget to the axis of rotation and one Side of the square is tangent to the axis of rotation. The rigid body is rotating counterclockwise about the axis.

Code: 
       |  
Square | circle
       |
Let | = the axis of rotation

The axis is not clearlly specified it just says, find its angular momentum about that axis.
 
nevermind everybody I figured it out. I used the parallel axis theorem and it worked out beautifully

Thanks
 
You must log in or register to reply here.
Top