Work done by cyclic process (thermodynamics)

AI Thread Summary
The discussion centers on calculating work done by a gas during a cyclic process in thermodynamics. The user seeks clarification on using the ideal gas law (PV=nRT) to determine the number of moles (n) and how to evaluate work under isothermal conditions. It is confirmed that n remains constant and can be derived from the equation, with the user calculating n as 14.440 when T=1. The conversation emphasizes setting pressure and volume conditions equal for both states in the process and integrating to find total work. The integration limits must be correctly ordered to accurately compute the work done.
cpatel23
Messages
16
Reaction score
0

Homework Statement


http://s9.postimage.org/5iw5rixyl/image.jpg
(sorry doesn't let me embed)

Homework Equations


P1V1=P2V2
and
PV=nRT

I know that Work done by gas from a --> b = (nRT)*Integral(V2/V1)
My question is do i use PV=nRT to find N? and if T is constant (isothermal) what do I plug in for T when evaluating work?

Using PV=nRT I got n= 14.440 when T=constant (1), is this correct?

I appreciate all of your help.
 
Last edited:
Physics news on Phys.org
bump. i really need help.
 
n is constant so you shouldn't need to worry about it.
(PV)/(nRT)=1 for both "a" and "b" so we can set them equal since they both equal 1.
=> P_f*V_f = P_i*V_i
Now you can solve for P_f since everything else is given.
At this point you can integrate from each initial to final (remember to set your integrals limits in the correct order). The total work is the sum of the individual work done on/by the system.
 
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Back
Top