A535 kg roller coaster car began at rest at the top of a 93.0 m hill. now it is at the top of the first loop- de - loop. this roller coasters track is nearly frictionless so, resistances can be ignored. using g= 9.81 m/s^2

The roller coasters, at that point in the first loop-de-loop, it has potential and kinetic energy according to the conservation of energy theorem, because is moving and it's at certain height still.

Remember that conservation of energy theorem states that the total energy of an object is constantly exchanging between potential and kinetic energy, and the total amount of energy is always constant, the variation is between these two energy, but the total amount is always the same.

So, when the roller coaster is at the initial point, it only has potential energy, it's total energy is potential only, because it's not moving. Then, when starts to move, the total energy is distributed into potential + kinetic energy.

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