### Angular momentum question... I have the answer

Posted:

**Thu Feb 20, 2014 2:47 pm**I just don't understand why the answer is like that. The prob is:

A uniform cylindrical puck of radius r and mass M is attached to the end of a cord that passes through a

hole in a fixed horizontal frictionless table. The center of the puck moves in a circle of

radius R with angular speed ω

8. The magnitude of the angular momentum of the puck about the hole is

So first I just calculate the Inertial moment of the pluck around the center of the table ,

I= Icylinder + M.R^2 = M(r^2/2 + R^2)

I would expect the answer: L to be simply that I times ω

but the correct answer is this WEIRD thing:

|L|= M (r^2/2 + R^2)^1/2 ω^2

I don't get it , where does that rootsquare term comes from and also why the ω^2????

Please help me out folks, I don't know what the heck am I doing wrong

A uniform cylindrical puck of radius r and mass M is attached to the end of a cord that passes through a

hole in a fixed horizontal frictionless table. The center of the puck moves in a circle of

radius R with angular speed ω

8. The magnitude of the angular momentum of the puck about the hole is

So first I just calculate the Inertial moment of the pluck around the center of the table ,

I= Icylinder + M.R^2 = M(r^2/2 + R^2)

I would expect the answer: L to be simply that I times ω

but the correct answer is this WEIRD thing:

|L|= M (r^2/2 + R^2)^1/2 ω^2

I don't get it , where does that rootsquare term comes from and also why the ω^2????

Please help me out folks, I don't know what the heck am I doing wrong