Finding Angular speed and momentum

[artsim2011]

Homework Statement

The problem:
A merry-go-round has a radius of 1.40m and a mass of 125kg. You may consider the merry-go-round to be a solid disk. A 60.0kg student stands on the outer edge of the merry-go-round, 1.40m from the center(the axis of rotation). It takes 3.00s for the merry-go-round and the student to make one revolution. The student then walks radially inward to a point 0.350m from the axis of rotation and stands at that point.
Find:
a. What is the initial angular speed of the merry-go-round, expressed in rad/s?
b. What is the angular momentum of the student and merry-go-round?
c. What is the final angular speed of the merry-go-round?

Homework Equations

L = I\omega^2
L(initial) = L(final)

The Attempt at a Solution

After I used the information given I have the final and initial angular speed of the merry-go-round and the student combined. I don't know what equation I have to use to get the angular speed of just the merry go round. Finally I'm not sure how to go about using the data to get the angular momentum. The I variable has three different ones the initial and final of the student and the merry-go-round itself and the same thing goes for the angular speed do I just add the two angular speeds that I already have or is there something else I have to do. If I'm not asking specific enough questions or if I need to post more information then please let me know and thanks for any responses.

 

[kuruman]

After I used the information given I have the final and initial angular speed of the merry-go-round and the student combined. I don't know what equation I have to use to get the angular speed of just the merry go round.

It is not clear what you mean by this. The angular speed of the merry-go-round is the same as the angular speed of the student at all times. Angular momentum is given by Iω where I = I_{merry-go-round} + I_student. As the student moves, I_student changes but I_{merry-go-round} does not.

Does this help?

 

[artsim2011]

Oh my god yes that helps I didn't understand they were the same I thought that they were different thank you so much.