<human>: I'm looking for a list of the most popular questions about physics.
<bot>: 
 • What is the speed of light?
 • How do you define momentum?
 • What is the difference between kinetic energy and potential energy?
 • What is the mass of an electron?
 • Why does a magnet attract iron?
 • What is the definition of entropy?
 • How do you calculate the volume of a cube?