Study Material
THERMODYNAMICS
Very Short Answer Questions
Q1. What is the difference between Thermal equilibrium and Thermodynamic equilibrium?
Q2. State Zeroth law of Thermodynamics.
Q3. What thermodynamic variables can be defined by Zeroth Law and First Law?
Q4. Write the sign convention for heat energy (Q) and work (W).
Q5. Why the internal potential energy of an ideal gas is zero?
Q6. Define specific heat capacity of the substance. On what factors does it depend?
Q7. Define one calorie and mechanical equivalent of heat.
Q8. Define molar specific heat capacity.
Q9. Write the specific heat relation for an ideal gas.
Q10. Why the coolant in a chemical or a nuclear plant should have high specific heat?
Q11. Define state variables and write the equation of state.
Q12. Which of the two will increase the pressure more, an adiabatic or an isothermal process, in reducing the volume to 50%?
Q13. What happens to its temperature, when a thermos flask containing a liquid is shaken vigorously?
Q14. Explain the Isochoric and Isobaric processes.
Q15. State second law of Thermodynamics.
Q16. What are the processes involve in a Carnot engine.
Q17. What is a PV diagram?
Q18. Can a room be cooled by leaving the door of an electric refrigerator open?
Q19. Why the escaping air appears cold, when the valve of a bicycle tube is opened in summer?
Q20. Why does the brake drum of an automobile get heated up while moving down at constant speed?
Q21. Why a heat engine with 100% efficiency can never be realized in practice?
Q22. State the Kelvin-Planck statement of second law of thermodynamics.
Q1. State and explain first law of thermodynamics.
Q2. Define two principal specific heats of a gas. Which is greater and why?
Q3. Derive a relation between the two specific heat capacities of gas on the basis of first law of thermodynamics.
Q4. Explain the drawbacks of First law of thermodynamics.
Q5. Write a short note on Quasi-static process.
Q6. Obtain an expression for the work done by an ideal gas during isothermal change.
Q7. Obtain an expression for the work done by an ideal gas during an adiabatic change.
Q8. Compare isothermal and adiabatic processes.
Q9. Draw the PV diagram for Isothermal, Adiabatic, Isobaric and Isochoric processes.
Q10. Obtain the relation between \(T\) and \(V\) for an adiabatic process.
Q11. Discuss about the Isochoric and Isobaric processes.
Q12. Explain reversible and irreversible processes.
Q13. Explain the cyclic and non cyclic processes with examples.
Q1. Derive the relation between \(C_p\) and \(C_v\) on the basis of First law of Thermodynamics. Determine the efficiency of a Carnot engine which is operating between \(127^\circ\mathrm{C}\) and \(327^\circ\mathrm{C}\).
Q2. Derive the expression for work done in an adiabatic process. When the heat energy of \(6\times10^5\,\mathrm{J}\) is supplied to an ideal gas at a constant pressure of \(10^5\,\mathrm{N\,m^{-2}}\), then volume of an ideal gas increased from \(3\,\mathrm{m^3}\) to \(5\,\mathrm{m^3}\). Calculate the change in internal energy of the gas.
Q3. Describe the working of a Carnot engine and obtain an expression for its efficiency. A Carnot engine whose efficiency is \(45\%\) takes heat from a source maintained at a temperature of \(227^\circ\mathrm{C}\), then find the temperature of sink.
Q4. State second law of Thermodynamics. How is heat engine different from a refrigerator. A heat engine takes in \(1420\,\mathrm{J}\) of heat from the source and exhausts \(660\,\mathrm{J}\) of heat to the sink. How much work is done by the engine?
Q1. If a monoatomic ideal gas of volume \(1\) litre at N.T.P. is compressed (i) adiabatically to half of its volume, find the work done on the gas. Also find (ii) the work done if the compression is isothermal. \((\gamma=5/3)\) \n(Ans: (i) \(-89\,\mathrm{J}\) (ii) \(W=-70\,\mathrm{J}\))
Q2. Five moles of hydrogen when heated through \(20\,\mathrm{K}\) expand by an amount of \(8.3\times10^{-3}\,\mathrm{m^3}\) under a constant pressure of \(10^5\,\mathrm{N\,m^{-2}}\). If \(C_v=20\,\mathrm{J\,mole^{-1}K^{-1}}\), find \(C_p\). \n(Ans: \(C_p=28.3\,\mathrm{J\,mole^{-1}K^{-1}}\))