Which form of energy is due to the movement of electrons?

What is the relationship between the wavelength of a wave and it's energy?

When you push downward on a book at rest on a table, you feel an upward force. does this force depend on friction? defend your answer.

The man of mass m1 and the woman of mass m2 are standing on opposite ends of the platform of mass m0 which moves with negligible friction and is initially at rest with s = 0. the man and woman begin to approach each other. derive an expression for the displacement s of the platform when the two meet in terms of the displacement x1 of the man relative to the platform.