Questions of the week: what is motion?

What is the function of the commutator in a dc motor? a. to spin the magnet b. to change direct current into alternating current c. to change alternating current into direct current d. to spin the wire coil

Oxygen and hydrogen gas are at the same temperature t.what is the ratio of kinetic energies of oxygen molecule and hydrogen molecule if oxygen is 16 times heavier than hydrogen.

Aman throws a football straight into the air. as it rises, it slows down. which type of energy is the football gaining?