Rotational motion energy

1. Dec 16, 2014

kaspis245

1. The problem statement, all variables and given/known data
Same mass sphere and cylinder are rolling on a horizontal plane. Which part of each objects kinetic energy does objects rotational energy make up?

2. Relevant equations
Erotational = 1/2 Iw2

Ekinetic = 1/2 mv2

3. The attempt at a solution

I know, that moments of inertia are:

Icylinder = 1/2 MR2

Isphere = 2/5 MR2

And I know that:

Etotal = Ek + Erotational

What sould I do?

Last edited by a moderator: Dec 16, 2014
2. Dec 16, 2014

Staff: Mentor

For rolling without slipping, how are $\omega$ and $v$ related?

3. Dec 16, 2014

kaspis245

Well, v = wR .

4. Dec 16, 2014

Staff: Mentor

Exactly. Use that to relate rotational and translational kinetic energy.