Question

0.08 kg air is heated at constant volume through 5°C. The specific heat of air at constant volume is 0.17 kcal/kg°C and J = 4.18 joule/cal. The change in its internal energy is approximately.

(1) 318 J

(2) 298 J

(3) 284 J

(4) 142 J

Answer 1

The correct option is (3) 284 J

\(Q = \Delta U\) as work done is zero [constant volume]

\(\Delta U = ms \Delta T\)

\(= 0.08 \times (170 \times 4.18) \times 5 \)

\(\simeq 284 J\)