Mechanical Engineering - Thermodynamics - Discussion
Discussion Forum : Thermodynamics - Section 1 (Q.No. 32)
32.
The value of gas constant (R) in S. I. units is
Discussion:
11 comments Page 1 of 2.
Srk said:
10 years ago
1005J/kg k AND Cv = 718 J/kg k.
But Cp-Cv = R.
1005-7158 = 287.
Therefore R = 287 J/kg k.
But Cp-Cv = R.
1005-7158 = 287.
Therefore R = 287 J/kg k.
(2)
Shubhangi Jojare said:
4 years ago
Gas constant R = 287 J/kgK.
Universal GAs const Ro = 8314 J/kgK.
Universal GAs const Ro = 8314 J/kgK.
(2)
BIKASH said:
1 decade ago
The question is R for air.
The universal gas constant value is R' = 8.314 Kj/Kg.K.
Gas constant R = R'/M (molecular mass of that gas).
For air molecular mass = 29 (0.78*28 + 0.21*32).
So R = 8.314/29 = 0.287 Kj/Kg. K or 287 J/Kg. K.
The universal gas constant value is R' = 8.314 Kj/Kg.K.
Gas constant R = R'/M (molecular mass of that gas).
For air molecular mass = 29 (0.78*28 + 0.21*32).
So R = 8.314/29 = 0.287 Kj/Kg. K or 287 J/Kg. K.
(1)
Geetha said:
1 decade ago
Cp = 1005J/kg k AND Cv = 718 J/kg k.
But Cp-Cv = R therefore R = 287 J/kg k.
But Cp-Cv = R therefore R = 287 J/kg k.
Yosef mulugeta said:
1 decade ago
This is not true.
pv = nRT, R = pv/nT = 1atm*22.4L/6.02*10(23 is the power of)*273.15K.
= 8.3L.atm/mol.K
cp/cv = R, this "R" is molar gas. not gas constant.
pv = nRT, R = pv/nT = 1atm*22.4L/6.02*10(23 is the power of)*273.15K.
= 8.3L.atm/mol.K
cp/cv = R, this "R" is molar gas. not gas constant.
Rahul kumar said:
9 years ago
Hi, the Cp & Cv values are different for different material.
Laxman said:
9 years ago
0.287 Kj/Kg is correct answer.
Engr Arshad jamali said:
9 years ago
287j/kgk is the correct answer.
Yogesh said:
8 years ago
287 j/ kg k is the gas constant only for air.
Machinist said:
7 years ago
Why are universal gas constant and gas constant for a particular gas used separately in different problems?which one is used where? Can anybody explain, please?
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