Homework Help: Rolling Cylinder

1. Jul 5, 2008

smilingsteph

My text book is not helping me on this, so I'd love some help.

A cylinder is rolling down a ramp, without slipping. I have the total kinetic energy, but now need to know the rotational kinetic energy and transitional kinetic energy at the bottom of the ramp.

I have the mass, radius, length, w, v, and I of the cylinder and the height and length of the ramp. I know it should be super easy at this point, as I know the total energy. But nothing's working. HELP! I have that: KE tot = 1/2 I x w^2 + 1/2 m x v^2. Any guidance?

2. Jul 5, 2008

Hootenanny

Staff Emeritus
Since the cylinder is rolling without slipping, can you relate the angular velocity to the linear velocity?

3. Jul 5, 2008

smilingsteph

yes i woudl assume so. v=vo + at to w=wo + alphaT

4. Jul 5, 2008

Hootenanny

Staff Emeritus
They weren't the equations I was thinking of, there is one equation which directly relates the angular velocity of a cylinder to the linear velocity of the surface of the cylinder.

5. Jul 5, 2008

smilingsteph

Ohhh really???? I was looking online for that and haven't had any luck so far. I'll continue to look! Thanks!!!!

6. Jul 5, 2008

Hootenanny

Staff Emeritus
Perhaps:

$$\omega =\frac{v}{r}$$

would help.

7. Jul 5, 2008

smilingsteph

ohhh ok thanks! i'll see if that works. THANKS!