Question

a motor produces less mechanical energy tha the energy it uses because the motor?

Answer 1

It loses some energy. Friction.

Answer 2

Yes, friction. It loses some of the energy due to heat. The expanding gases in the engine are in contact with parts of the engine. Simply due to this contact, there is heat flow because they're at different temperatures. Consider the laws of Thermodynamics. Entropy!

0: Any two systems of differing temperature in contact with each other will spontaneously approach the same temperature.

1: Conservation of energy.

2: Entropy. Many different ways to say it... All systems approach equilibrium... All systems approach a state of greater disorder... You can't make a perfect heat engine... S = klog(W)...

Answer 3

Motor vs engine

Answer 4

The second law of thermodynamics says it is impossible to convert all of the energy into the motor to useful work. Some energy is wasted (exhausted) to the surrounding environment as heat. This increases the entropy or surrounding disorder.

Answer 5

What the above said. In general no system will ever be 100% efficient, so you will never get as much energy out as you put in.