Polytropic Process: Finding Final Pressure and Volume

AI Thread Summary
The discussion focuses on a polytropic process involving hydrogen gas in a piston-cylinder setup. The initial conditions include a pressure of 100 kPa, temperature of 765°C, and a volume of 0.35 m³, with a final volume of 8.0 m³ after the process. Participants clarify that the relevant equation for this process is PV^n = constant, allowing for the calculation of final pressure and volume. The mass of the gas has been determined, and the final pressure has been calculated, but there is confusion regarding the final volume. The key takeaway is the application of the polytropic equation to find the necessary values.
Mohd17
Messages
3
Reaction score
0

Homework Statement



A frictionless piston cylinder contains ideal gas hydrogen , R = 4.125 KJ/Kg.K , initially at p1=100 Kpa , t1 = 765 C , V1 = 0.35 m3 . The gas undergoes a polytropic process with n = 1.22 until the final volume becomes V2=8.0 m3

Cp = 14.3338 , Cv= 10.2043 , [URL]http://www.taftan.com/thermodynamics/GAMMA.GIF[/URL] = 1.4

Find :
a) Mass of the ideal gas
b) Final pressure and volume of the gas
 
Last edited by a moderator:
Physics news on Phys.org
You need to post your attempt.

What relevant equations do you think are needed here?
 
the problem how can i get the volume of the gas !

already i get the answers for part a and the final pressure
 
Mohd17 said:
the problem how can i get the volume of the gas !

already i get the answers for part a and the final pressure

You should know for a polytropic process PVn = constant.
 
sorry but i didin't understand ...
now what's the answer ?
 
Mohd17 said:
sorry but i didin't understand ...
now what's the answer ?

PVn = constant means that

P1V1n = P2V2n

You were given P1, V1, n and you found P2.
 

Thread 'Errors and significant figures'

I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
View full post »
Thread 'Collision of a bullet on a rod-string system: query'

Thread 'Collision of a bullet on a rod-string system: query'

In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...
View full post »
Thread 'A cylinder connected to a hanging mass'

Thread 'A cylinder connected to a hanging mass'

Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
View full post »

Similar threads

What are the steps to solve a polytropic process problem?
Replies
6
Views
2K
Thermally insulated container with alternating series of walls
Replies
49
Views
2K
Trouble solving for end state of two control volumes in a rigid tank
Replies
12
Views
2K
Ideal Gas Equation and Polytropic Constant
Replies
3
Views
5K
How Is Work and Heat Transfer Calculated in a Polytropic Process for Helium Gas?
Replies
3
Views
7K
Adiabatic Expansion of Pressurized Air in a Piston-Cylinder Setup
Replies
8
Views
2K
Work Done in a polytropic process
Replies
3
Views
5K
Is My Solution for Part D Logically Correct?
Replies
7
Views
2K
Mixing two ideal gases with different V, T at constant pressure
Replies
16
Views
3K
Final temperature of an adiabatic process between two reservoirs
Replies
25
Views
4K

Hot Threads

Recent Insights

Back
Top