BSc Physics SEM III ATKT PHYSICS PAPER 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 1 A spring stretches by 5cm when a mass of 2Kg is suspended at one end, The spring constant is: 12 marks
   • a) SOON/m 234. 392. 400 N/m 2 At what rate must the fuel burn to give a 20kg rocket an acceleration of 1g The efficiency of a Carnot engine is temperature of the sink is
   • a) OK b) 100 K 273 None of these 4 The thermodynamic scale of temperature does not have
   • a)OK b) 10K c) 100K 5 Cy = 4 then the value of y is 6 In Otto engine, the spark plug fires shortly before the following stroke
   • a) compression expansion
   • B) Answer in one sentence 1 Define logarithmic decrement Give the Kelvin— Planck statement of the second law of Which substance is used in Diesel engine as a working substance? 3
   • C) the Blanks 5
   • 1. The projection of Uniform Circular motion on the diameter is 2 As damping increases the resonant frequency The entropy of the universe is process is necessarily quasistatic 5 Incase of substance that contracts on melting, < iS
2. Q2 A) Attempt any one up the equation for damped harmonic oscillator. Solve it and show that the motion is oscillatory when damping is small 2 Write the equation of motion for a rocket motion. From this get the expression for maximum velocity 8 marks
   • B) Attempt any one Derive the time period for a compound pendulum. Show that the point of suspension and point of oscillation are interchangeable 2 Write the equation for forced damped oscillation. Solve this to get the expression for amplitude. Also get the expression for maximum 8
   • C) Attempt any one Acharged capacitor of 1.8mF discharges through an inductance of 0.5H What should be the maximum value of the resistance so that the discharge 2 Three particles of mass 2kg each has a position vectors given by 2ti ro= and r3= (t-1)i+2tj+2tk. Find the position of the center of mass and its velocity at 4
3. Q3 A) Attempt any one 1 Draw the T—S diagram of the Carnot cycle and describe each stage 2 State the Carnot’s theorems and prove them 8 marks
   • B) Attempt any one 1 Show 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 engine operating between the same two temperatures Starting with the equation TdS = + pdV obtain the expressions for changes in the entropy of an ideal gas in various processes 8
   • C) Attempt any one 1 A Carnot engine whose sink temperature is C has an efficiency of 40%. It is desired to increase the efficiency to 50%. Obtain the increase in temperature of the source Explain how the size of a degree is determined in the thermodynamic scale of temperature? 4
4. Q4 A) Attempt any one is Joule-Thomson effect? Show that Joule-Thomson expansion is an 2 an expression for efficiency of an Otto cycle with neat labeled p-V 8 marks
   • B) Attempt any one a note on properties and uses of liquid helium 2 the working Diesel engine with the help of its p-V diagram 8
   • C) Attempt any one Calculate the depression in the melting point of ice produced by 2 atmosphere increase in pressure. Given : Latent heat of ice = 80 cal/g, Change in specific volume of transition from ice to water at 2 the efficiency of a Diesel engine for which the adiabatic compression ratio is 16 and adiabatic expansion ratio is 4. Take y=1.4 Attempt any Four (20) 1 A mass m is suspended from a spring of force constant k. If the natural frequency is twice the damping frequency, show that the damping constant 2 A nucleus emits an alpha particle and is converted to If the velocity of the alpha particle is 1.5X10’ m/s and the kinetic energy is 4
   • 4.5MeV, calculate the recoil velocity and the kinetic energy of the a short note on reversible and irreversible processes Obtain an expression for energy that is not available for work in an 5 Considering entropy as a function of temperature and volume, prove that 6 Write a note on Unattainability of absolute zero

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