Question

A great deal of effort, time, and money has been spent in the quest for the so-called perpetual-motion machine, which is defined as a hypothetical machine that operates or produces useful work indefinitely and/or a hypothetical machine that produces more work or energy than it consumes. Explain, in terms of heat engines and the first law of thermodynamics, why or why not such a machine is likely to be constructed.

a) Such a machine is likely; Heat engines always produce more work than consumed.

b) Such a machine is unlikely; Heat engines always consume more work than produced.

c) Such a machine is likely; First law of thermodynamics allows perpetual motion.

d) Such a machine is unlikely; First law of thermodynamics prohibits perpetual motion.

Answer 1

A perpetual-motion machine, which produces more work or energy than it consumes, is unlikely to be constructed due to the first law of thermodynamics and the nature of heat engines. Option d) Such a machine is unlikely; First law of thermodynamics prohibits perpetual motion is the correct answer.

Step-by-step explanation:

The quest for a perpetual-motion machine, which is a machine that operates or produces useful work indefinitely or produces more work or energy than it consumes, has been ongoing for a long time. However, such a machine is unlikely to be constructed due to the first law of thermodynamics and the nature of heat engines.

The first law of thermodynamics, also known as the law of conservation of energy, states that energy cannot be created nor destroyed, but it can only change forms. In the case of a heat engine, it converts heat energy into mechanical work. However, according to the first law of thermodynamics, the amount of work produced by a heat engine is always less than the amount of heat energy it consumes.

Heat engines operate based on the principle of heat transfer from a high-temperature source (Qh) to a low-temperature sink (Qc). The work produced by the engine is represented by W, and the heat energy consumed by the engine is represented by Qh. According to the first law of thermodynamics, the work produced by the engine is equal to the difference between the heat energy absorbed and the heat energy released: W = Qh - Qc. This means that the work produced by a heat engine is always less than the heat energy it consumes.

Therefore, the correct option is d) Such a machine is unlikely; the first law of thermodynamics prohibits perpetual motion.