When the roller coaster cart is at the top of the roller coaster, which best describes its energy.

When the roller coaster is at the very peak of it upward motion, it stops for a very short moment. It can no longer go any further upwards.

That being so, there (in theory) can be no kinetic energy. But there is energy: the coaster does not stay stopped. It has full potential energy described by mgh. M and g are constants. The height (h) is at a maximum. The upward gravitational kinetic energy is at a minimum -- 0.

answer: the metamorphic rocks are formed when they are exposed to high pressure and high temperatures. this happens when one of the earth's plates comes in contact with the other plate by traveling in opposite directions, straight into each other or slipping under one another. the friction that is caused by this activity results in   melting of rocks and when it cools they are known as metamorphic rocks. this process needs a controlled amount of pressure and temperature otherwise it may turn into magma.