The energies of electrons are said to be quantized. explain what this means. explain.

To move from one energy level to another, an electron must gain or lose just the right amount of energy. Electrons are said to be quantized because they need a quantum of energy to move to a different sublevel. ... When atoms absorb energy, electrons move into higher energy levels.

Friction is the force that act and opposes all motion of moving objects

Sound energy is produced when an object vibrates. examples are 1- a balloon popping2-a whistle3- a waterfall