# Work Done

## Trending Questions

**Q.**List I describes thermodynamic processes in four different systems. List II gives the magnitudes (either exactly or as a close approximation) of possible changes in the internal energy of the system due to the process.

List -I | List -II | ||

(I) | 10–3 kg of water at 100∘C is converted to steam at the same temperature, at a pressure of 105 Pa. The volume of the system changes from 10–6 to 10–3 in the process. Latent heat of water =2250 kJ/kg. | (P) | 2 kJ |

(II) | 0.2 moles of a rigid diatomic ideal gas with volume V at temperature 500 K undergoes an isobaric expansion to volume 3V. Assume R=8.0 J mol−1K−1. |
(Q) | 7 kJ |

(III) | One mole of a monoatomic ideal gas is compressed adiabatically from volume V=13 m3 and pressure 2 kPa to volume V8 | (R) | 4 kJ |

(IV) | Three moles of a diatomic ideal gas whose molecules can vibrate, is given 9 kJ of heat and undergoes isobaric expansion. | (S) | 5 kJ |

(T) | 3 kJ |

Which one of the following options is correct?

- I→S, II→P, III→T, IV→P
- I→Q, II→R, III→S, IV→T
- I→T, II→R, III→S, IV→Q
- I→P, II→R, III→T, IV→Q

**Q.**A cylinder of ideal gas is closed by an 8 kg movable piston (area 60 cm2). Atmospheric pressure is 105 Pa. When the gas is heated from 30°C to 100°C, the piston rises by 20 cm. The piston is then fixed in its place and the gas is cooled back to 30°C. Let ΔQ1 be the heat added to the gas in the heating process and |ΔQ2| the heat lost during cooling. Then the value of ΔQ1−|ΔQ2| will be

- 0
- 136 J
- −136 J
- −68 J

**Q.**Consider the cyclic process ABCA as shown in the figure, 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 A total of 1200 J of heat is withdrawn from the sample in the process.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 magnitude of the work done (in joules) by the gas during the part BC. (R=8.3 JK−1mol−1)

- 2580 J
- 3625 J
- 4520 J
- 1550 J

**Q.**The gas inside a spherical bubble expands uniformly and slowly so that its radius increases from R to 2R. Let the atmospheric pressure be P0 and surface tension be S. The work done by the gas in the process is

- 28πP0R33+24πSR2
- 25πP0R33+24πSR2
- 28πP0R33+23πSR22
- none of these

**Q.**A vertical cylinder piston system has cross-section S. It contains 1 mole of an ideal monatomic gas under a piston of mass M. At a certain instant a heater is switched on which transmits heat q per unit time of the cylinder. Assume the piston is in equilibrium at all times during the process. The velocity v of the piston given the condition that pressure under the piston is constant and the system is thermally insulated is xq5S(Po+MgS). Here the value of x is

**Q.**During an integral number of complete cycles, a reversible engine (shown by a circle) absorbs 1200 joule from reservoir at 400 K and performs 200 joule of mechanical work.

(a) Find the quantities of heat exchanged with the second reservoir.

(b) Find the change of entropy in second reservoir (in J/K).

(c) What is the change in entropy of the universe?

**Q.**An ideal monoatomic gas is taken around the cycle ABCDA as shown in the PV diagram. The work done during the cycle is given by

- 12PV
- PV
- 2PV
- 4PV

**Q.**An ideal gas is taken through the cycle A→B→C→A, as shown in the figure. If the net heat supplied to the gas in the cycle is 5 J, the work done by the gas in the process C→A is

- −5 J
- −15 J
- −10 J
- −20 J

**Q.**Two moles of an ideal monoatomic gas at 27∘C occupies a volume of V. If the gas is expanded adiabatically to the volume 23/2V, then the work done by the gas will be (γ=53, R=8.31 J/mol K)

- 3739.5 J
- 2627.23 J
- 2500 J
- −2500 J

**Q.**Find the work done by the system in closed path ABCA as shown below.

- −(p2−p1)(V2−V1)2
- (V1−V2)(p1−P2)
- (p2+p1)(V2−V1)2
- Zero