A rollercoaster is designed such that it starts off from rest at a height of $60$m above the ground. then moves along a frictionless track toward a big 360-degreeree loop. The height at the top of the loop is $25$m$,$ and the weight of the car plus passengers is $900$kg$.$

$10\mathrm{.}1$  What is the speed when the rollercoaster enters the loop at ground level?

$10\mathrm{.}2$  What is the speed at the top of the loop $(20$m$)?$