What is the essential reason that all perpetual motion machines fail?

a. Perpetual motion machines must create energy in order to do useful work, and energy cannot be created.
b. Perpetual motion machines must at least preserve all the energy in a system, and some is always lost.
c. Perpetual motion machines run on gasoline, and gasoline is not a renewable resource.
d. A perpetual motion machine necessarily removes heat from a single-temperature environment.
e. Perpetual motion machines have to contend with friction, which destroys energy.


b

Physics & Space Science

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