– Why really can’t a machine convert the whole part of energy given to it into work? What causes a fraction of it to be lost, even when there’s no dissipative forces?

Question

– Why really can’t a machine convert the whole part of energy given to it into work? What causes a fraction of it to be lost, even when there’s no dissipative forces?

In: 0

Answer 1

There are always dissipative forces. Friction. Air resistance. Electrical resistance. Elastic deformation.

Physics textbooks like to do all their work on perfectly rigid bodies in frictionless vacuums at absolute zero, but your machinery is going to work on elastic bodies in a filthy factory on a humid day in Atlanta.

Things deform and grind and resist, and then they heat up. This heat radiates away into the abyss and is lost forever.