# Kinetic energy expressed with angular velocity

I'm studying the chapter Energy on Kleppner's book.

There we have an example of a Conical Pendulum.

It is said that it moves with constant angular velocity $\omega$ in a circle of constant radius $R$. Then they say that the kinetic energy $K = \frac 1 2 M R \omega^2$.

But, since $v = \omega R$, shouldn't it be $K = \frac 1 2 M R^2 \omega^2$?

• It could be a typo, because the units are not correct in the first expression. Nov 18 '15 at 16:08
• Yes you are correct, the first one has wrong dimensions on either side of the equation. Nov 18 '15 at 16:13
• yes, the expression you wrote is correct (not the one in the book)
– user83548
Nov 18 '15 at 17:34
• It must be that the book should have $K = \frac 1 2 M (R \omega)^2$ but they forgot to typeset the parenthesis, Dec 30 '18 at 22:13