A system goes from i to f by path iaf, absorbing Q = 50 cal and doing W = 20 cal. Along path ibf it absorbs Q = 36 cal. Find the work done along ibf (cal).
Physics · Mixed Chapter
JEE Main Practice

Question

A system goes from i to f by path iaf, absorbing Q = 50 cal and doing W = 20 cal. Along path ibf it absorbs Q = 36 cal. Find the work done along ibf (cal).

G1 Physics · Accepted Answer

Step 1: Along iaf, ΔU = Q − W = 50 − 20 = 30 cal. Step 2: Internal energy is a state function, so ΔUᵢ→f is 30 cal for path ibf too. Step 3: Wᵢᵦf = Qᵢᵦf − ΔU = 36 − 30 = 6 cal.