Thermo Phy

[smoky raft]

This question makes no sense to me

[abstract cedar]

<@&1227987967939838003>

Note for OP

+solved @user1 @user2... to close the thread when your doubt is solved. Mention the users who helped you solve the doubt. This will be added to their stats.

[smoky raft]

if i assume it to be a triangle

net work will be area inclosed

so 10 x 2 x 1/2

= 10j

so surely net work done has to be lesser than this

but instead its 205J how tf

and also it says temp is 27C so 300k But where is it 300k at no point A or B does it give 300K

[winged zodiac]

Bro isothermal hai. Both an and b will be same temp.

Also this is a real gas.

So integral pdV will change.

[sharp coyote]

Isn't it a general polytropic process?

[winged zodiac]

Yep

But. Temp is constant. From a to b right.

They are saying temp is maintained at 27 deg

[sharp coyote]

They said 'at 27°C' which could mean initial temp as well right?

[winged zodiac]

it is cylic. so 'initially' does not figure here, I think.

instead of PV = nRT it follows this, and like in the derivation you use P = nRT/V, here you use RT/(V^3)

then integrate :)

area under triangle you are assuming it follows PV = nRT btw :D
@smoky raft

[smoky raft]

what

work is integration of Pdv

and that will be

area inclosed

isnt that right

what does that have to do with PV = nRT

[smoky raft]

ye that is a solution i wanted to know why this not work

[smoky raft]

it says PV^3 = RT for path AB

At A , P = 20 , V= 2
20 x 8 = 160 = RT

At B P = 10 , V = 4
10 x 64 = 640 = RT

its not same temp

[winged zodiac]

Bro p is dependent on v. they aren’t independent variables. The relationship is usually pv = nrt. Here it is not.

yea T not being constant complicates things :D

you will get a differential eqan in dP and dV

then you would need specific heat capacities, thoda complicate ho jayega

weird that this is a pyq that too this year ka

did folks get bonus marks on this?

[smoky raft]

ye but isnt work done Integral of pdv

i am getting so confused

[rapid sentinel]

so ig the work done for a-b should be nrdeltaT/1-x since its a polytropic process

or p2v2-p1v1/1-x

yuh thats better

104-202/1-3

wait what

0

and work done of ac is 0 cuz its isochoric

so net work done ig should be of only bc which would 10(-2)=-20? 💀

ig im wrong

leave

[winged zodiac]

yea this is incorrect, T A != TB

[winged zodiac]

this tracks. but since P, V, T are varying you have to make approximations here, even if you do that and do what you did works

[winged zodiac]

polytropic would mean that PV^n = constant, here it is not na since T is varying?

[winged zodiac]

not polytropic :D

[rapid sentinel]

Yeah I realized that after I sent my msgs

[rapid sentinel]

Also uh

If pv=nrt

And pv^3=rt

Does did mean v2=1/n so volume is constant?

But it clearly isn't constant

Wth

[winged zodiac]

This is not true since it is a real gas

[rapid sentinel]

Oh nvm i didn't read that

[smoky raft]

ok

+solved @winged zodiac