Question

An inventor claims to have developed an engine that takes in 1000 J of heat and produces 1500 J of work during each cycle. Comment on the validity of this claim.
A. The proposed engine claims to produce more work in a cyclic process than the amount of heat that is supplied, so it is in violation of the first law of thermodynamics.
B. The statement is completely valid as it increases efficiency by increasing the work output.
C. The proposed engine claims to produce more work in a cyclic process than the amount of heat that is supplied, so it is in violation of the zeroth law of thermodynamics.
D. None of these.

Answer 1

The zeroth law of thermodynamics states that if in two bodies each are in thermal equilibrium with the third body, then these two bodies will also be in equilibrium.
The first law of thermodynamics says that when energy passes in or out of a system, then the system’s internal energy changes in accordance with the law of conservation of energy.
The second law of thermodynamics states that in all energy exchanges, if no energy enters or leaves the system, then the potential energy of the state will be less than that of the initial state.

Complete step by step answer:
Given that the inverter develops 1500 J of work during each cycle when the engine takes in just 1000 J of heat, therefore we can say the engine claims to produce more work in the cyclic process than the amount of heat is supplied.
Thus we can say this is the violation of the first law of thermodynamics, which is the version of the law of conservation of the total energy of an isolated system.
We know the law of conservation of energy of an isolated system is constant where energy can be transferred from one form to another but can neither be created nor be destroyed.
Option A is correct.

Note: Students must note that in a system, heat supplied to a system must always be more than work done by the system.