Question

Calculate δe, if q= 0.764 kj and w= -830 j . express your answer using two significant figures.

Answer 1

Given:
Q = 0.0764 kJ = 764 J, heat input
W = -830 J, useful work done

From the 1st Law of Thermodynamics, the change in internal energy is
δE = Q - W
     = 764  - (-830)
     =  1594 J = 1.594 kJ

Answer: 1.59 kJ (two sig. fig.)