Question

An electric scooter has a battery capable of supplying 120 Wh of energy. If friction forces and other losses account for 60.0% of the energy usage, what altitude change can a rider achieve when driving in hilly terrain, if the rider and scooter have a combined weight of 890 N

Answer 1

First, we need to convert Wh to joules. This can be easily done. Wh means that you are doing 1W of work per hour. We need to find out how much work this is.
$1Wh=1\cdot3600J\\ 120Wh=120\cdot 3600J=432 KJ$
We lost 60% of this energy on friction and other losses which means that this leaves us with:
$E=432\cdot0.4=172.8KJ$
We are going to use this energy to do work against the force of gravity. This means that when we reach our maximum height all of our energy will be used and thus converted the potential energy in the gravitational field.
$E=mgh\\ h= \frac{E}{mg}=\frac{172.8\cdot 10^3}{890}=194,16m$