2. The motion of roller coasters depends upon the conversion of potential and kinetic energy. A 200 kg car starts from rest at the top of a hill with a
height of 30 m.
Which of the following is this car's kinetic energy at the bottom of the hill?

58,800 Joules

Explanation:

I used the formula for Potential energy which is PE = mgh

200 kg x 9.8 m/s^2 x 30 m = 58,800 J

At the very tops of the rollercoaster is maximum PE which is 58,800 J and 0 J of KE, but at the very bottom is maximum KE (kinetic energy) which is 58,800 Joules but 0 J of PE. This is because energy can not be destroyed ONLY converted

positive reinforcement? ?

the displacement produced by the body.  

the amount of force subjected to the body.  

the angle between the direction of force and displacement