1.
Given : T1 = 50°c , T2 = 80°c
Solution:
(a) constant volume
Q = dU + W
Q = dU + pdV
Q = dU + 0 [ volume is constant, so dV=0]
i.e. Qv = McvdT
Where cv is the specific heat due at constant volume
(b) Constant pressure
Q = dU+ W
= dU + dPv
= d(U+Pv)
Q = dH
= McpdT
Where cp is the specific heat at constant pressure.
i.e. QP = McpdT
Conclusion:
Since work done is zero in case of constant volume process , all heat supplied is used in increasing the internal energy of the system and temperature rises. But in case of constant pressure process, a part of heat supplied is used in the work done ( or increasing the volume of system). So more amount of energy is required in constant pressure process to increase the temperature of the gas.
Also we know that , cp > cv , so more amount of energy is required for constant pressure process.
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