Thermodynamics Question: Calculating Work for Nitrogen Gas Expansion

  • Thread starter Thread starter PGall
  • Start date Start date
  • Tags Tags
    Thermodynamics
AI Thread Summary
The discussion revolves around a thermodynamics problem involving the expansion of nitrogen gas. The user calculates initial parameters including mass, temperature, pressure, and volume, ultimately determining the work done during expansion. The confusion arises regarding the mention of "50% of the isobaric work," leading to questions about the implications of temperature changes on work done. It is clarified that the process is not strictly isobaric but that the work done is only half of what it would be in a true isobaric scenario. Understanding this distinction is crucial for accurately characterizing the process and calculating the final state variables.
PGall
Messages
1
Reaction score
0
I have this problem:

Two (2) kilograms of Nitrogen gas at 600 K and 10 atm are allowed to expand such that they end up occupying three (3) times the initial volume and providing 50% of the isobaric work.

mass = 2000 g
temp1 = 600 K
pressure1 = 1013250 Pa
gasC = 8.3144621
n = mass/28.0134 = 71.3944 mol
v1 = (n*gasC*temp1)/pressure1 = 0.351506 m^3
v2 = 3*v1 = 1.05452 m^3

w = p1*(v2 - v1) = 712327 J

I have to determine v2, temp2, and pressure2 and characterize the process. Where I'm confused is the 50% of isobaric work part. If the system is isobaric wouldn't all of the work being done be a result of the change in volume? Or am I missing something related to a change in temperature that would affect the work being done?

Any help would be greatly appreciated.
 
Last edited:
Engineering news on Phys.org
An isobaric process is a thermodynamic process in which the pressure stays constant.
Your question does not say the process is isobaric, but that the work is 50% of that had the process been an isobaric expansion.
 
After over 25 years of engineering, designing and analyzing bolted joints, I just learned this little fact. According to ASME B1.2, Gages and Gaging for Unified Inch Screw Threads: "The no-go gage should not pass over more than three complete turns when inserted into the internal thread of the product. " 3 turns seems like way to much. I have some really critical nuts that are of standard geometry (5/8"-11 UNC 3B) and have about 4.5 threads when you account for the chamfers on either...
Thread 'Physics of Stretch: What pressure does a band apply on a cylinder?'
Scenario 1 (figure 1) A continuous loop of elastic material is stretched around two metal bars. The top bar is attached to a load cell that reads force. The lower bar can be moved downwards to stretch the elastic material. The lower bar is moved downwards until the two bars are 1190mm apart, stretching the elastic material. The bars are 5mm thick, so the total internal loop length is 1200mm (1190mm + 5mm + 5mm). At this level of stretch, the load cell reads 45N tensile force. Key numbers...
Thread 'What type of toilet do I have?'
I was enrolled in an online plumbing course at Stratford University. My plumbing textbook lists four types of residential toilets: 1# upflush toilets 2# pressure assisted toilets 3# gravity-fed, rim jet toilets and 4# gravity-fed, siphon-jet toilets. I know my toilet is not an upflush toilet because my toilet is not below the sewage line, and my toilet does not have a grinder and a pump next to it to propel waste upwards. I am about 99% sure that my toilet is not a pressure assisted...
Back
Top