Thermal Physics-prop,thermo,kinetic theory

Question 1

What is molar specific heat (c)?

Answer 1

Heat supplied to raise the temp. of 1 mole of gas by 1°C is called molar specific heat(c).
• C=Q/nΔT

Question 2

Cv for any gas is equal to

Answer 2

fR/2

Question 3

For cyclic process Q=W.

T/F

Answer 3

True.

• ΔU =0 (bcz initial & final positions are same i.e,ΔT=0 )

Question 4

For any gas, ΔU equals

Answer 4

ΔU = fnRT/2

Where f is the degree of freedom of that gas.

Question 5

State first law of thermodynamics?

Answer 5

Q= ΔU + W

Where Q is the heat supplied “into” the system; ΔU is change in internal energy and W is work done “by” the gas.

Question 6

Under normal conditions, what is the value of f for

a) monoatomic gas
b) diatomic gas
c) triatomic gas

Answer 6

Monoatomic, f=3
Diatomic, f=5
Triatomic, f=6 (non-linear)

Question 7

What is efficiency of a cyclic process?

Answer 7

Efficiency (η)= work done/heat input = W/Qi

*heat input=total heat absorbed

Question 8

Give the relation b/w pressure and volume in case of an adiabatic process?

Answer 8

PV^γ =const.

Where γ is Cp/Cv for that gas

Question 9

Work done in an adiabatic process is given by

Answer 9

W = (P1V1 - P2V2)/γ-1

Question 10

Give day-to-day example of adiabatic processes and other special processes.

Answer 10

All fast processes can be considered adiabatic, and other slow processes can be included as isothermal,isobaric,isochoric depending on which one is const.-T,P,V.

Question 11

Work done in isothermal process is given by

Answer 11

W = nRT ln(V2/V1)

= nRT ln(P1/P2)

Question 12

What is a polytropic process?

Answer 12

When PV^N is const.
# Where N is the power to which volume is raised on having PV = const.

Question 13

Work done for a polytropic process id given by

Answer 13

W = (P1V1 - P2V2)/N-1

= - (N R ΔT)/ N-1

Question 14

Heat supplied for a polytropic process is

Answer 14

Q = n ΔT ( Cv - R/N-1)

Question 15

Molar heat capacity for polytropic process is

Answer 15

C = Cv - R/N-1