Question

If 315cal of heat is given to the system, and the system does 20cal of work, find the change in internal energy.

(a) 295cal

(b) 335cal

(c) 0 cal

(d) 335J

I have been asked this question by my college director while I was bunking the class.

I need to ask this question from First Law of Thermodynamics in division Thermodynamics of Physics – Class 11

Answer 1

Correct choice is (a) 295cal

To elaborate: The first law states that ΔU=ΔQ – ΔW

= 315 – 20

= 295cal.

Work is positive as it is done by the system. Heat is positive as it is supplied to the system.