Question

We consider a thermodynamic system. If ∆U represents the increase in its internal energy and W, the work done by the system; which of the following statements are true?

(a) ∆U=-W in an isothermal process

(b) ∆U=W in an isothermal process

(c) ∆U=-W in an adiabatic process

(d) ∆U=W in an adiabatic process

I have been asked this question during a job interview.

I want to ask this question from Thermal Equilibrium topic in chapter Kinetic Theory of Gases of Engineering Physics I

Answer 1

Right answer is (c) ∆U=-W in an adiabatic process

Easy explanation: In an adiabatic process,

∆Q=0

∆U=∆Q-∆W=0-W=-W.