Question

A rollercoster car and passengers of total mass 1800kg starts from rest at 80m above the ground. Ignoring air resistance and friction what will the speed be:

At ground level
At top of the next peak which has height of 30m
Take gravity 10N/kg
i calculated it as 1697m/s, by converting gravitational potentional energy to kinetic energy to calculate the velocity/speed.
Did you do the same?

Answer 1

m*g*h=(m*v^2)/2
v^2=2*m*g*h/m
v^2=2*g*h
v^2=2 * 10 m/s^2 * 80 m
v^2=1600 m^2/s^2
v=40 m/s