How does a rollercoaster convert potential energy into kinetic energy and then back to potential energy again and again?

While standing outdoors one evening, you are exposed to the following four types of electromagnetic radiation: yellow light from a sodium street lamp, radio waves from an am radio station, radio waves from an fm radio station, and microwaves from an antenna of a communications system. rank these type of waves in terms of increasing photon energy.

Metals are good conductors of electricity because they

Suppose two stars are located in region a of the h-r diagram shown in the figure below. star c appears much dimmer than star y as seen from earth. which star can be inferred to be nearer to earth and how do you know?