Neglecting friction and air resistance, the first hill must be built 4 times higher than it is now.
Explanation:
4a)the displacement is the distance moved in a direction but since no direction is given, the displacement is equal to the distance
b) the distance moved is 400m because that's the length of the track
P=change in E/t
Change in E=p*t
=15*3
=45
The answer is 45J.
