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.
Yash said:
6 years ago
Cp = R+Cv.
CP = 1.00 kJ/kg.K.
Cv = 0.718 kJ/kg.K.
CP = 1.00 kJ/kg.K.
Cv = 0.718 kJ/kg.K.
Nitish said:
7 years ago
Cp = Cv for liquids.
And Cp>Cv for gases.
And Cp>Cv for gases.
SAMBASIVA said:
7 years ago
Cp/Cv is greater than 1 so, Cp gerater than Cv.
Engr Arshad jamali said:
9 years ago
The value of cp always greater than cv because the relationship is cp - cv = R.
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)
Punit Kongi said:
10 years ago
Just imagine an IC engine.
At Cv-volume is constant, so if you give the heat (Q) to this, the piston does not move until total heat is being supplied.
At Cp-pressure will be constant, so the same heat (Q) what you are giving to will do addition work i.e. the piston will move down in this case to keep the pressure constant in this case.
Therefore Cp>Cv.
At Cv-volume is constant, so if you give the heat (Q) to this, the piston does not move until total heat is being supplied.
At Cp-pressure will be constant, so the same heat (Q) what you are giving to will do addition work i.e. the piston will move down in this case to keep the pressure constant in this case.
Therefore Cp>Cv.
Manzoor ahmed mir said:
10 years ago
Kindly explain in simple method.
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.
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.
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.
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