I think I get it now. He's now referring to the formula distance = 2πr when he talks about dividing by time. Thanks alot! Now that I understand that I will be able to continue.
In the equations in my original post K is kinetic energy. So in words "Rolling kinetic energy is equal to translational kinetic energy plus rotational kinetic energy".
I can understand the method you just showed, that works out pretty simple. But I still don't see how the equations in the...
Homework Statement
Question comes from this book http://www.anselm.edu/internet/physics/cbphysics/index.html
In the section on rotational energy it gives the formula K_{rolling} = K_{translational}+K_{rotational} which it then expands to K_{rolling} = \frac{1}{2}mv^{2} + \frac{1}{2}Iω^{2}...