# Time derivatives

by Fellowroot
Tags: derivatives, time
 Math Emeritus Sci Advisor Thanks PF Gold P: 39,348 I take that your "dot" refers to differentiation with respect to time, t,- I will use a prime since it is simpler here- and you are asking about the derivative of $(\theta')^2$. The derivative of any $(f(t))^2$ with respect to t is $2f(t)f'(t)$, by the chain rule, so the derivative of $(\theta(t)')^2$ is $2(\theta')(\theta'')$.