1. Seven grams of helium (molecular mass = 4.0026 u) expand isothermally at 340 K and does 9760 J of work. Assuming that helium is an ideal gas, determine the ratio of the nal volume of the gas to the initial volume. 2. The work done by Four moles of a monatomic ideal gas (y = 5/3) in expanding adiabatically is 880 J. The initial temperature and volume of the gas are 390 K and 0.150 m3. What is the nal temperature of the gas. K 3. The work done by four moles of a monatomic ideal gas (1' = 5/3) in expanding adiabatically is 880 J. The initial temperature and volume of the gas are 390 K and 0.150 m3. What is the nal volume of the gas? [Hint: For an adiabatic process => T1V17_1 = T211271 ] m3 4. A Carnot engine operates with an efficiency of 26% when the temperature of its cold reservoir is 270 K. Aesuming that the temperature of the hot reservoir remains the same, what must be the temperature of the cold reservoir in order to increase the efficiency to 44%? K 5. An ideal heat engine takes in heat from a reservoir at 360 DC and has an efciency of 29%. If the exhaust temperature does not vary and the efciency is increased to 49%, what would be the increase in the temperature of the hot reservoir? C 6. A heat engine operates at 46% of its maximum theoretical (Carnot) efciency. If the temperature of the hot and cold reservoirs are 390 C and 70 C, respectively, what is the efciency of the engine? % 7. Sound propagating through air at 31 C passes through a vertical cold front into air that is 3.9 C. If the sound has a frequency of 2500 Hz, by what percentage does its wavelength change in crossing the boundary? % 8. Suppose that sound is emitted uniformly in all directions by a public address system. The intensity at a location 25.0 m away from the sound source is 2.90 X 10"1 W/mz. What is the intensity at a spot that is 84.0 m away? W/m1 9. A door bell generates a 48.0 dB sound at a close distance. What is the intensity of the sound generated by the bell at the same distance? W/m2 10. The sound intensity levels for a machine shop and a quiet library are 90 dB and 38 dB, respectively. What is the difference between the intensity of the sound in the machine shop and that in the library? W/m2