I need help with both the questions

Which of the following are properties of mechanical waves? check all that apply ⭕️ particles of the medium move back and fourth, but do not move with the wave. ⭕️ the particles of the medium always move parallel to the wave motion. ⭕️ wave motion begins with a disturbance in the medium. ⭕️ waves transport energy from a source outward, away from the source.

If the ama of the inclined plane below is 2, calculate the ima and efficiency. ima = efficiency =

Why is the energy that results from a roller coaster's position at the top of a hill referred to as potential energy?