I did this in P2 a few months ago: The roller coaster has speed, kinetic energy (movement energy and potential energy. As the roller coaster goes up, there is a increase in potential energy. At the top of the 'hill' thingy, there is maximum potential energy and as it goes down the kinteic energy builds up.
Hope this helps x
Oh if you are taking Physics P2 I have a very handy mindmap in my resources that I made and it helped me a lot. Feel free to check it outt :)