Thermodynamics Questions along with solutions (Questions for IITJEE)

Question 1:A gas is contained in a vertical, frictionless piston cylinder device. The piston has a mass of 20 kg with a cross-sectional area of 20 cm² and is pulled with a force of 100N. If the atmospheric pressure is 100 kPa, determine the pressure inside.


Question 2:A piston-cylinder device has a ring to limit the expansion stroke. Initially the mass of Oxygen is 2 kg at 500 kPa, 30° C. Heat is now transferred until the piston touches the stop, at which point the volume is twice the original volume. More heat is transferred until the pressure inside also doubles. Determine the amount of heat transfer and the final temperature.


Question 3: A piston cylinder device contains 1 kg of oxygen at 150 kPa, 30°C. The cross-sectional area of the piston is 0.1 m². Heat is now added causing gas to expand. When the volume reaches 0.2 m³, the piston reaches a linear spring with a spring constant of 120 kN/m. More heat is added until the piston rises another 25 cm. Determine the final pressure, temperature and the energy transfers.


Question 4:Is the energy of the system U an intensive or extensive variable?



Question 5:Suppose we have M+N systems prepared, and the first is in thermal equilibrium with the second, the second in thermal equilibrium with the third, etc., until system M+N- 1 is in thermal equilibrium with the M+Nth system. Is the first system in thermal equilibrium with the M+Nth?


Question 6:A gas is contained in a cylinder with a moveable piston on which a heavy block is placed. Suppose the region outside the chamber is evacuated and the total mass of the block and the movable piston is 102 kg. When 2140 J of heat flows into the gas, the internal energy of the gas increases by 1580 J. What is the distance s through which the piston rises?


Question 7:A resistance thermometer is such that resistance varies with temperature as
R_T=R₀(1+aT+bT⁵)
where T represent Temperature on Celsius scale And a,b,R₀ are constants.R₀ unit is ohm
Based on above data ,Find out the unit of a,b


Solutions

Please take a look at other Thermal post
Thermal Expansion
Study Tips Part 1
Study Tips Part 2
Thermo Quick Recap
Conceptual Questions Part 1
Conceptual Questions Part 2
Conceptual Questions Part 3
Conceptual Questions Part 4
IITJEE Objective Questions part 1
IITJEE Objective Questions Part 2
Thermal Expansion Problems
IITJEE Subjective Questions
Thermo Questions

Conceptual question for Thermodynamics

PART 3

1.In a given process of an ideal gas,dW=0 and dQ<0 ,then for a gas
a.dT <0
b. dV>0
c.dP=0
d. dT>0

2.what is true for a free expansion process
a. dW=0
b. dQ=0
c. dU=0
d. all the above

3. Consider the following two statement
A.If heat is added to the system,it temperature must increase
B.If dW >0 then dV >0
a A & B both are correct
b A is correct only
c. B is correct only
d A &B both are wrong

4.what is true of Isothermal process
a. dT>0
b. dT=0
c. dQ=dW
d. none of the above

5. if dU=-dW for a process,the process is
a. Adiabatic
b. Isothermal
c. Isobaric
d. None of the abobe

6.What is true of a cyclic process
a.ΔQ=ΔW
b ΔU=0
c.ΔU >0
d None of the above

7. An ideal gas is taken from state A(P,V) to state B(P/2,2V) along a straight line path in P-V diagram.Select the correct statement from the following
a.The workdone by the gas in process A to B exceeds the work that would be done by it if the system were taken from A to B along a isotherm
b.in the T-V diagram ,the path AB becomes a part of a parabola,
c. In the P-T diagram,the path becomes a part of a parabola
d.In going from A to B,the temperature T of the gas first increase to a maximum and then decrease

8.Let W₁,W₂ are the workdone in the two process A & B by an ideal gas.ΔT_A=ΔT_B. Let C_A and C_B are the molar heat capacities in two process
Also W₁ > W₂. whic of the following is correct
a.C_A=C_B
b.C_A < C_B
c. C_A > C_B
d None of the above.

9.which of the following is correct
a. Molar heat capacity is 0 for PV^y=Constant
b. Molar heat capacity is infinity in adiabatic process
c. Internal energy does not change in Isothermal Process
d. All the above

10.An ideal gas is taken from state A(P₁,V₁) to state B(P₂,V₂) by two method X & Y..which of the following is correct
a.ΔQ₁-ΔW₁=ΔQ₂-ΔW₂
b.ΔU₁=ΔU₂
c. ΔQ₁+ΔW₁=ΔQ₂+ΔW₂
d. None of the above

Solutions

Please take a look at other parts also
Conceptual Questions Part 1
Conceptual Questions Part 2
Conceptual Questions Part 4

Some study tips for Thermodynamics

1. Always make sure you Heat(Q) ,Internal Energy(U) & Work(W) with correct sign in equation
ΔU=Q-W

W is positive when work done by the system(Increase in Volume)
W is negative when work done on the system(Decrease in Volume)
Q is positive when heat is given to the system
Q is negative when heat is taken from the system

2. workdone in a cycle is equal to the area enclosed on the PV diagram

3. Change in Internal energy is zero for a cycle
So Net Heat=Net Work done

4.All Bodies emit radiation at all temperature.Radiation emmited are of diffrent frequencies.Frequency at which most radiation are emmitted are directly proportional to Temperature of the body.