University:
Concordia University Wisconsin
Course:
PHYS 1524 | General Physics II
Academic year:

2023
Views:

100

Pages:

3
Author:

gewoekerdodx

THERMODYNAMICS 1. Zeroth law of thermodynamics If two system are each in thermal equilibrium with a third, they are also in thermal equilibrium with each other. 2. First law of thermodynamics Heat supplied (Q) to a system is equal to algebraic sum of change in internal (U) of the system and mechanical work (W) done by the system.  Q = W + U [ Here W= PdV : ΔU = nCv ΔT ] Q = W + dU For differential change path dependent 3. path independent Sign convention Heat absorbed by the system  Positive Heat rejected by the system  Negative Increase in the internal energy (i.e. rise in temperature)  Positive Decrease in the internal energy (i.e. fall in temperature)  Negative Work done by the system  Positive Work done on the system  Negative 4. For cyclic process U = 0  Q = W 5. For isochoric process V = constant  P  T & W = 0 Q = U = µCvT 6. For isobaric process P = constant  V  T & W = 0 Q = µCpT, U = µCvT W = P(V2 – V1) = µRT 7. For adiabatic process PV = constant or T γ P1-γ = constant or TV γ-1 = constant In this process Q = 0 and W = –ΔU = µC v (T1 -T2 ) = P1V1 – P2 V2 γ –1 THERMAL PROPERTIES OF MATTER 8. For Isothermal Process T = constant or T = 0  PV = constant In this process U = µCvT = 0 9. V  P  So, Q = W = µRT l n  2   µRT l n  1   V1   P2  For any general polytropic process PVx = constant (a) Molar heat capacity C  Cv  (b) Work done by gas W  (c) Slope of P-V diagram R 1 x nR(T1  T2 ) ( PV  PV )  1 1 2 2 x 1 x 1 (also known as indicator diagram at any point 10. dP P =–x ) dV V Efficiency of a cycle  Q -Q Q Work done by working substance W = 1 2 = 1– 2 = Heat supplied Q1 Q1 Q1 Q1 Source T1 Working substance Q2 Sink T2 W 11. For carnot cycle 12. For refrigerator Q 2 T2  Q1 T1 Certificate pf performance β = Source T1 so η = 1– Q2 T =1– 2 Q1 T1 Q2 Q2 T2 = = W Q1 – Q 2 T1 –T2 Q1 Working substance Q2 Sink T2 W 13. Bulk modulus of gases B P ΔV  V Isothermal bulk modulus of elasticity,  P  BIT = –V    V T = constant Adiabatic bulk modulus of elasticity,  P  BAD γV   BBAD γBITIT AD= –γV AD γB  V  14. Work done is least for monoatomic gas (adiabatic process) in shown expansion. P Isobaric Isothermal Diatomic Monoatomic Adiabatic V 15. Air quickly leading out of a balloon becomes cooler as the leaking air undergoes adiabatic expansion. 16. First law of thermodynamics does not forbid flow of heat from lower temperature to higher temperature. 17. First law of thermodynamics allows many processes which actually don’t happen. P P W W Positive negative 18. V 19. V Carnot Engine It is a hypothetical engine with maximum possible efficiency Process 1  2 & 3  4 are isothermal Process 2  3 & 4  1 are adiabatic P QS 1 2   1 4 QR 3 V T3 – 4 T1 – 2