Q.
A gas is taken from state-1 to state-2 along the path shown in figure. If 70 cal of heat is extracted from the gas in the process, calculate the change in internal energy of the system (in J).
see full answer
Want to Fund your own JEE / NEET / Foundation preparation ??
Take the SCORE scholarship exam from home and compete for scholarships worth ₹1 crore!*
An Intiative by Sri Chaitanya
answer is 241.5.
(Unlock A.I Detailed Solution for FREE)
Ready to Test Your Skills?
Check your Performance Today with our Free Mock Test used by Toppers!
Take Free Test
Detailed Solution
We know work done by a gas is given by the area under PV-curve or the area between PV-curve and the volume axis. Generally, we take volume on x-axis while plotting V-curve but in figure it is taken on y-axis thus the work done is given by the shaded area shown in figure. In this process volume of gas decreases thus work is done on the gas and it is given asW=−12×1.5×10−4×(2+5)×105=−52.5JIt is given that heat extracted in the process is 70 cal, thus Q=−70 cal=70×4.2 J=−294 JNow from first law of thermodynamics, we haveQ=W+ΔUor ΔU=Q−W=(−294)−(−52.5)=−241.5JThus in the process internal energy of gas decreases by 241.5 J
Watch 3-min video & get full concept clarity