In a refrigerator, one removes heat from a lower temperature and deposits to the surroundings at a higher temperature. In this process, mechanical work has to be done, which is provided by an electric motor. If the motor is of 1kW power, and heat is transferred from `-3^@ C to 27^@C`, find the heat taken out of the refrigerator per second assuming its efficiency is 50% of a perfect engine.

Gasoline has an enthalpy of combustion 24000 kJ/mol gallon. When gasoline burns in an automobile engine, approximately 30% of the energy released is used to produce mechanical work. The remainder is lost as heat transfer to the engine's cooling system. As a start on estimating how much heat transfer is required, calculate what mass of water could be heated from 25^(@)C to 75^(@)C by the combustion of 1.0 gallon of gasoline in an automobile? (Given : C(H_(2)O)=4.18 J//g^(@)C ) a) 34.45 kg b) 80.383 kg c) 22 kg d) 224 kg

Consider a PV-diagram in which the path followed by one mole of perfect gas a cylindrical container is shown in (fig.). Given to internal enregy for one mole of gas at temperature T is (3 // 2) RT,find the heat supplied to the gas when it is taken from state 1 to 2,with V_2=2V_2 .

A 10 kW drilling machine is used to drill a bore in a small aluminium block of mass 8.0 kg. How much is the rise in temperature of the block in 2.5 minutes, assuming 50% of power is used up in heating the machine itself or lost to the surroundings. Specific heat of aluminium = 0.91 J g^-1 ^@C^-1

A molecule of a substance has a permanent electric dipole moment of magnitude 10^(-29) C m. A mole of this substance is polarized at low temperature by appling a strong elecrostatic field of magnitude 10^(6) V m^(-1) . The direction of the field is suddenly changed by an angle of 60^(@) . Estimate the heat released by the substance in aligning its dipole along the new direction of the field. For simplicity, assume 100% polarisation of sample.