Question

What is the main reason that no machine can be 100% efficient?

(1 point)
Responses

The output energy of a machine is always designed to be less than the input energy.
The output energy of a machine is always designed to be less than the input energy.

Some input energy is always converted into non-useful forms like heat due to friction.
Some input energy is always converted into non-useful forms like heat due to friction.

Machines are built to create a small amount of extra energy during their operation.
Machines are built to create a small amount of extra energy during their operation.

Energy is often destroyed by the machine's moving parts, preventing full efficiency.
Energy is often destroyed by the machine's moving parts, preventing full efficiency.

Answer 1

Some input energy is always converted into non-useful forms like heat due to friction.

Explanation: Real machines have losses (friction, sound, internal heating, etc.), so not all input energy can be converted to useful output—this follows from practical losses and the second law of thermodynamics.