Question

Does the Law of Conservation of energy apply to machines?

• A. No, as machines require a constant input of energy in order to work
• B. Yes, the energy required to maintain motion is balanced by the energy lost to friction
• C. No, as machines can create energy from motion
• D. Yes, but only to perpetual motion machines
• E. No, as the law would apply to only perpetual motion machines

Answer 1

Answer: (A)

No, as machines require a constant input of energy in order to work

Machines require input work to be done on them, which increases the potential, or kinetic energy, or both, of the system.

However this work is done on the machines by external systems that utilize their energies to convert them to work.

So even though Law of Conservation of Energy holds for the entire system as a whole, it does not stand for the machines alone.