Why can’t the high-quality energy released from a lump of burning coal be recycled?

Which is not a source of noise pollution? a)airplanes b)acid rain c)machines d)cars

Asolid cylinder and a cylindrical shell have the same mass, same radius, and turn on frictionless, horizontal axles. the cylindrical shell has light-weight spokes connecting the shell to the axle. a rope is wrapped around each cylinder and tied to blocks of equal masses that are held the same height above the ground. both blocks are released simultaneously. the ropes do not slip. which block hits the ground first? or is it a tie?

The flow of electrons from one atom to another is called