Question

Whenever a system undergoes a cyclic change, the algebraic sum of work transfer is proportional to the algebraic sum of heat transfer as work and heat are mutually convertible. Which law of thermodynamics suggests this?

(a) Zeroth law of thermodynamics

(b) Second law of thermodynamics

(c) Third law of thermodynamics

(d) First law of thermodynamics

This question was posed to me during an internship interview.

I need to ask this question from Working Principles of I.C Engine topic in chapter Internal Combustion Engine of Farm Machinery

Answer 1

Correct answer is (d) First law of thermodynamics

Best explanation: For closed system, a change in the energy content is the algebraic difference between the heat supply, Q, and the work done, W, during any change of state. The energy may include many types of energies including kinetic, potential, electrical etc., but from thermodynamic point of view these energies are ignored and the energy due to rise in temperature is considered.