Certain amount of an ideal gas `(gamma = 1.4)` performs 80J of work while undergoing isobaric expansion. Find the amount of heat absorbed by the gas in the process and the change in its internal energy.

Explanation

For n mol of a gas,
`pV = nRT or, pdV = nRdT [ :.` p constant]
or, `dW = nRdT or, dT = (dW)/(nR)` ….(1)
Also, `(C_p)/(C_v) = gamma or, (C_(p)-C_(v))/(C_v) = (gamma - 1)/(1)`
or, `C_(v) = (nR)/(gamma - 1) [ :. C_(p) - C_(v) = nR]` ….(2)
We know, change in internal energy,
`dU = C_(v)RT` ....(3)
From (1), (2) and (3)
`dU = (nR)/(gamma - 1) xx (dW)/(nR) = (80)/(1 - 1.4) = 200 J`.