Mechanical Engineering - Thermodynamics - Discussion
Discussion Forum : Thermodynamics - Section 1 (Q.No. 26)
26.
The value of specific heat at constant pressure (cp) is __________ that of at constant volume (cv).
Discussion:
15 comments Page 1 of 2.
Sourabh said:
10 years ago
Consider the piston cylinder arrangement and supply heat to it.
In constant pressure process piston is free to move as p is constant so drag force is neglected it means there will be increase in internal energy and boundary work.
In constant volume process: All the energy will be used to raise the internal energy as the boundary work is zero.
So cp is greater then cv always.
In constant pressure process piston is free to move as p is constant so drag force is neglected it means there will be increase in internal energy and boundary work.
In constant volume process: All the energy will be used to raise the internal energy as the boundary work is zero.
So cp is greater then cv always.
(1)
Sameer Satpathy said:
1 decade ago
Cp>Cv since,
Cp-Cv = R,
Cp = R+Cv.
Where R is a specific gas constant which is positive so Cp is greater than Cv.
Cp-Cv = R,
Cp = R+Cv.
Where R is a specific gas constant which is positive so Cp is greater than Cv.
Sudharshan Reddy K said:
1 decade ago
Because Cp=gama(Cv) which implies Cv should be multiplied with "Gama" to get Cp.
Pavan said:
1 decade ago
Cp/Cv = Y(gamma),
Gamma should be greater than 1.
Gamma should be greater than 1.
Dilip Kumar Kanoujia said:
1 decade ago
In const vol process w = pdv become zero so that's why cp>cv?
Swajan manna said:
1 decade ago
Cp-Cv=R so Cp is more.
Arjun said:
1 decade ago
When gas is heated at Constant Pressure (Cp) it requires more heat energy as there is change is in internal energy as well as external work done.
But in case of Constant Volume (Cv) there is no external work done, so that the given heat has to increase only external energy. Therefore Cp is always greater than Cv.
But in case of Constant Volume (Cv) there is no external work done, so that the given heat has to increase only external energy. Therefore Cp is always greater than Cv.
Y.ganesh said:
1 decade ago
At temperature 300 k, the values of air is:
Cp = 1.005 kj/kg.
Cv = 0.718 kj/kg.
Cp = 1.005 kj/kg.
Cv = 0.718 kj/kg.
Maqusud alam said:
1 decade ago
At constant pressure there is temperature increase as well as external work done by the system against atmosphere but in constant volume external work done is zero so Cp is greater than Cv.
Manzoor ahmed mir said:
10 years ago
Kindly explain in simple method.
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