Under real conditions, not all mechanical energy converted in blocks and levers is converted into mechanical work

Under real conditions, not all mechanical energy converted in blocks and levers is converted into mechanical work. What kind of energy is always converted into a part of the expended energy in any mechanism?

In real conditions, there is always a friction force, which is most often not taken into account when solving problems in physics in order to simplify the calculations performed. Due to the friction force, the contacting parts of the mechanisms are heated, respectively, there is an increase in the thermal energy of the bodies.

Therefore, the correct answer: in any mechanism, part of the energy is always converted into heat energy (due to the action of the friction force).