BSc Physics SEM III 2018 2019 2019 Physics I Question Paper - Mumbai University | munotes

Questions asked in this paper

• (2) Figures to the right indicate maximum marks

1. Q1 A) Select correct answer Oscillations are damped due to the 12 marks
   • d) driving force 2 Minimum time period of a compound pendulum is given by 3 A Carnot engine whose source temperature is 400 K takes 500 calories of heat at this temperature and rejects 400 calories of heat to the sink. The temperature of the sink is 4 process is necessarily
   • a) quasi b) non-dissipative c) non-static none of these 5 of substances that expands on melting, dP/dT is
   • a) positive b) negative Cc) zero d) none of these 6 According to third law of thermodynamics it is not possible to attain the
   • a) b)OK c) d) and
   • B) Answer in one sentence Give the expression for the time period of a compound pendulum Give the Clausius statement of the second law of thermodynamics 3 If Diesel and Otto engines have same compression ratio then which one is Fillin the Blanks (5) Energy of a damped harmonic oscillator decreases with 3
   • 2. Steady state displacement and the driving force are in phase for
   • 3. The entropy cannot be destroyed but it can be 4 temperatures do not exist on the thermodynamic scale 5 The process in the porous plug experiment is
2. Q2 A) Attempt any one up the differential equation for a forced damped harmonic oscillator Show that its solution consists of a transient term and a steady state term 2 Describe any two methods of characterizing a damped motion 8 marks
   • B) Attempt any one is reversible compound pendulum? Derive Bessel’s formula to calculate using it 2 that “If no external force acts on the system then the linear momentum of the system of particles remains conserved” 8
   • C) Attempt any one the advantages of a compound pendulum over a simple pendulum 2 natural frequency of mass vibrating on a spring is 20 Hz while its frequency with damping is 16 Hz. Find the logarithmic decrement 4
3. Q3 A) Attempt any one the statements of the Carnot’s theorem and prove them 2 that the ratio of any two temperatures on the thermodynamic scale of temperature is equal to the ratio of heat absorbed and heat rejected by a reversible heat engine operating between these two temperatures 8 marks
   • B) Attempt any one 1 State and prove the Clausius theorem Draw the T—S diagram of a Carnot cycle. Explain each stage of the cycle. Deduce the expression for efficiency of the Carnot cycle 8
   • C) Attempt any one What is the change in entropy when 10 kg of water at is converted into steam at the same temperature? ( Given:- Latent heat of steam = 540 cal/g ) Explain how the size of a degree is determined on the thermodynamic 4
4. Q4 A) Attempt any one 1 Describe the working of Otto engine with the help of its p-V diagram Write the Maxwell’s general equation. From this derive the four 8 marks
   • B) Attempt any one With the help of a neat diagram explain the liquefaction of helium by 2 Rankine cycle and derive an expression for its thermal efficiency 8
   • C) Attempt any one where is volume coefficient of expansion 2 Write a short note on the properties of Helium Attempt any Four (20) the concept of center of mass of a system of particles 2 Show that centres of suspension and centers of oscillation in a compound pendulum are mutually interchangeable Give the expressions for entropy change between two states of an ideal gas in various forms 4 Obtain an expression for unavailable energy in an irreversible process 5 The helium gas suffers Joule-Thomson expansion at Does the gas show a heating effect or cooling effect? (Given:- R = 0.083 atm.lit/mol.K, 6 Calculate the change in the efficiency of an Otto engine if the compression ratio is increased from 8 to 10. (Given: y = 1.4) 4

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