# Homework Help: Rotational Motion

1. Nov 13, 2004

### PinkDaisy

I'm having a problem with the following question:

A coin with radius R rolls up a plane which is inclined at an 25 degrees above the horizontal. The coin starts up the incline with an initial angular velocity of 70 rad/s and rolls in a straight line without slipping. How far will the coin roll up the incline?

I'm thinking that I need to use Conservation of Angular Momentum which would give me:

.5mv^2 + .5Iw^2 = mgh

then I manipulate to get h, plugging in .5mR^2 for I of the coin
h = (.5mv^2 + .5 (.5mR^2)w^2)/mg

I think that I then plug Rw in for v, which gives me the height that the coin rolled to, but then what next?

2. Nov 13, 2004

### CartoonKid

Then you apply the triangle formula to find the distance travelled up the incline since you know the inclination and 1 side of the triangle.