JEE Main & Advanced Physics Thermodynamical Processes Question Bank

done Numerical Value Type Questions - Thermodynamics Total Questions - 15

• question_answer1)
  A gas can be taken from A to B via two different processes ACB and ADB. When path ACB is used 60 J of heat flows into the system and 30J of work is done by the system. If path ADB is used work done by the system is 10 J. The heat (in joule) flow into the system in path ADB is:
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• question_answer2)
  Two Carnot engines A and B are operated in series. The first one, A receives heat at \[{{T}_{1}}(=600K)\]and rejects to a reservoir at temperature\[{{T}_{2}}\]. The second engine B receives heat rejected by the first engine and in turn, rejects to a heat reservoir at\[{{T}_{3}}(=400K)\]. Calculate the temperature \[{{T}_{2}}\] in kelvin if the work outputs of the two engines are equal:
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• question_answer3)
  For the given cyclic process CAB as shown for gas, the work done (in joule) is:
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• question_answer4)
  A sample of an ideal gas is taken through the cyclic process abca as shown in the figure. The change in the internal energy of the gas along the path ca is - 180 J, The gas absorbs 250 J of heat along the path ab and 60 J along the path bc. The work done (in joule) by the gas along the path abc is :
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• question_answer5)
  \[1.0{{m}^{3}}\]of water is converted into\[1671{{m}^{3}}\]of steam at atmospheric pressure and \[100{}^\circ C\]temperature. The latent heat of vapourisation of water is\[2.3\times {{10}^{6}}J/kg\]. If 2.0 kg of water be converted into steam at atmospheric pressure and \[100{}^\circ C\] temperature, then how much will be the increase in its internal energy (in joule)? Density of water is \[1.0\text{ }\times {{10}^{3}}\text{ }kg/{{m}^{3}}\], atmospheric pressure\[=1.01\times {{10}^{5}}N/{{m}^{2}}.\]
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• question_answer6)
  Air is contained in a piston - cylinder arrangement as shown in Fig. with a cross - sectional area of \[4\text{ }c{{m}^{2}}\]and an initial volume of 20 cc. The air is initially at a pressure of 1 atm and temperature of \[20{}^\circ C.\] The piston is connected to a spring whose spring constant is\[~k\text{ }=\text{ }{{10}^{4}}\] N/m, and the spring is initially undeformed. How much heat (in joule) must be added to the air to increase the pressure to 3 atm. (For air,\[{{C}_{V}}=\text{ }718\]\[J/kg{}^\circ C\] molecular mass of air 28.97)            
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• question_answer7)
  Consider the cyclic process ABCA, shown in Fig. performed on a sample of 2.0 mole of an ideal gas. A total of 1200 J of heat is withdrawn from the sample in the process. Find the work done (in joule) by the gas during the part BC.
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• question_answer8)
  A motor car tyre has a pressure of 2 atmosphere at room temperature of\[27{}^\circ C\]. If the tyre suddenly bursts, find the resulting temperature (in kelvin).
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• question_answer9)
  A Carnot engine whose heat sink is at \[27{}^\circ C\]has an efficiency of 40%. By how many degrees should the temperature of the source be changed to increase the efficiency by 10% of the original efficiency?
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• question_answer10)
  Five moles of an ideal gas taken in a Carnot engine working between \[100{}^\circ C\] and \[30{}^\circ C\]. The useful work done in one cycle is 420 joule. If the ratio of the volume of the gas at the end and beginning of the isothermal expansion is \[\frac{115}{x}\]. Find the value of x. (Take \[R=8.4\text{ }J/mol.K\])
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• question_answer11)
  How much energy in watt hour may be required to convert 2 kg of water into ice at\[0{}^\circ C\], assuming that the refrigerator is ideal? Given temperature of freezer is\[-15{}^\circ C\], room temperature is \[25{}^\circ C\]and initial temperature of water is\[25{}^\circ C\].
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• question_answer12)
  Helium gas goes through a cycle ABCDA (consisting of two isochoric and isobaric lines) as shown in figure. Find efficiency of this cycle. (Assume the gas to be close to an ideal gas)
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• question_answer13)
  Find the amount of work done (in joule) to increase the temperature of one mole of an ideal gas by \[30{}^\circ C\] if it is expanding under the condition \[V\propto {{T}^{2/3}}.\,\,\,(R=1.99\text{ }cal/mol-K)\] 
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• question_answer14)
  A thin U - tube sealed at one end consists of three bends of length \[l=250mm\] each, forming right angles. The vertical parts of the tube are filled with mercury to half the height. All of mercury can be displaced from the tube by heating slowly the gas in the sealed end of the tube, which is separated from the atmospheric air by mercury. Determine the work done (in joule) by the gas there by if the atmospheric pressure is \[{{P}_{0}}={{10}^{5}}\] Pa, the density of mercury is \[{{\rho }_{mer}}=13.6\times {{10}^{_{3}}}kg/{{m}^{3}}\], and the cross-sectional area of the tube is \[S=1c{{m}^{2}}.\]
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• question_answer15)
  A Carnot engine having a perfect gas as the working substance is driven backward and is used for freezing water already at\[0{}^\circ C\]. If the engine is driven by a 500 W electric motor having a efficiency of 60 %, how long (in seconds) will it take to freeze 15 kg of water. Take \[15{}^\circ C\]and \[0{}^\circ C\] as the working temperatures of the engine and assume there are no heat losses in the refrigerating system. Latent heat of ice \[=333\times {{10}^{3}}J/kg.\]
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