Consider non-dimensional equation for the height at the highest point is given by

\begin{equation} h(\mu)= \frac{1}{\mu}- \frac{1}{\mu^2} \log_e(1+\mu) \end{equation}

$0<\mu\ll 1.$

Determine to $O(\mu)$, the (non-dimensional) time for the body to travel from the highest point to the ground, and determine an estimate for the (non-dimensional) speed of the body when it returns to the ground, again to $O(\mu)$.

=> I really don't how to start this question. please help me.