How to solve this type of problems


Ans Is 3R

13 Answers

1
kunl ·

49
Subhomoy Bakshi ·

Cv=Rγ-1

for a gas, γ=1+2f

so, Cv=Rf2

f=degree of freedom.!

in the given question,

n.C.dT=Q
ΔU=nCvdT=Q2

so, nCdT=2nCvdT

C=2Cv
so, C=Rf

for a monoatomic gas, f=3

Thus, cprocess=3R

1
kunl ·

first solution u posted is not correct

49
Subhomoy Bakshi ·

what is the answer?

21
Shubhodip ·

because he made a small mistake in integrating ! check out

49
Subhomoy Bakshi ·

LOL!! yaaaaaa! :P :P

21
Shubhodip ·

1) C = Cv + kT2

dQ/ndT = dU/ndT + kT2

dQ - dU = kT2 ndT

dW = kT2ndT (1st law of thermo dynamics )

nRT dV/V = kT2ndT

R dV/V = kT dT

Now integrate

21
Shubhodip ·

2)dQ = dU + dW

For this particular process dQ = Q

dU = Q/2 = nCvdT (because change in internal energy is independent of the path)

we know C = dQ /ndT

after putting values we get C = 2 Cv = 3R

49
Subhomoy Bakshi ·

C = Cv + kT2

C= Cv + 1nPdVdt

so..
1nPdVdt=kT2

RTVdVdT = kT2

RdVV = kTdT

Rln(V2V1)=k2(T22-T12)

or,

RlnV-kT2/2=constant!!! :D

that is the process!

lnV=C+k2RT2

or..

V=C_{o}e^{kT^2/2R}

49
Subhomoy Bakshi ·

reposted the corrected equation!

49
Subhomoy Bakshi ·

we know...
Q=U+W

nCdT=nCvdT+Pdv!

tht gives the equation I used!

21
Shubhodip ·

little mistake in the final calculation it should be

R ln v - kt2/2 = constant

1
fahadnasir nasir ·

little mistakes in the above soln

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