HC Verma - Concepts of Physics Part 2

Book: HC Verma - Concepts of Physics Part 2

Chapter: 27. Specific Heat Capacities of Gases

Subject: Physics - Class 12th

Q. No. 2 of Exercises

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5g of a gas is contained in a rigid container and is heated from 15°C to 25°C. Specific heat capacity of the gas at constant volume is 0.172 cal g–1°C–1 and the mechanical equivalent of heat is 4.2 J cal–1. Calculate the change in the internal energy of the gas.


Mass of the gas(m) = 5g

Change in temperature(dT) = 10°C

Specific heat at constant volume(Cv) = = 0.172 cal g–1°C–1

Mechanical equivalent of heat = 4.2 J cal–1

Formula used:

Change in internal energy = mCvdT


m = Mass of the gas

Cv = Specific heat at constant volume

dT = Change in temperature

Also, we know,

Heat(Joule)= Mechanical equivalent of heat× Heat(cal)

Putting the values in the above formula, we get

= (5x10x0.172) cal

= 8.6 cal = (8.6x4.2)J

= 36.12 J (Answer)

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