AP EAPCET 08-Jul-2022 Shift 1 Paper

In a cyclic process, change in internal energy is zero.
⇒∆U=0
Hence, by first law of thermodynamics
‌ ∆ Q=∆ U+∆ W $
∆Q=∆W ( ∵ ∆ U=0) $
Now, work done by a gas = area under pV graph.
Also work done is negative if cycle is anticlockwise.
In given cycle, area =

1

2

×BC×AC
=

1

2

(20−5)×(30−10)
=

1

2

×15×20=150N−m
So, work done in 10 such complete cycles
=−10×150
=−1500J=−1.5‌kJ
Heat absorbed = Work done
=−1.5‌kJ