Related InterviewSolutions

• Convert the following reading of pressure to kPa, assuming that the barometer reads 760mm Hg.(1) 90cm Hg gauge (2) 40cm Hg vacuum (3) 1.2m H2O gauge
• If the efficiency of a power plant goes up as the low temperature drops why not let the heat rejection go to a refrigerator at say –10°C instead of ambient 20°C?
• A heat transfer requires a temperature difference, see chapter 4, to push the Q.. What implications do that have for a real heat engine? A refrigerator?
• At certain locations geothermal energy in undergound water is available and used as the energy source for a power plant. Consider a supply of saturated liquid water at 150°C. What is the maximum possible thermal efficiency of a cyclic heat engine using this source of energy with the ambient at 20°C? Would it be better to locate a source of saturated vapor at 150°C than use the saturated liquid at 150°C?  
• A drag force on an object moving through a medium (like a car through air or a submarine through water) is Fd = 0.225 A ρV2. Verify the unit becomes Newton.  
• A manometer shows a vacuum of 260 mm Hg. What will be the value of this pressure in N/m2 in the form of absolute pressure and what will be absolute pressure (N/m2), if the gauge pressure is 260 mm of Hg. Explain the difference between these two pressures.
• In a cylinder–piston arrangement, 2kg of an ideal gas are expanded adiabatically from a temperature of 125°C to 30°C and it is found to perform 152KJ of work during the process while its enthalpy change is 212.8KJ. Find its specific heats at constant volume and constant pressure and characteristic gas constant.
• Determine the size of a spherical balloon filled with hydrogen at 30°C and atmospheric pressure for lifting 400Kg payload. Atmospheric air is at temperature of 27°C and barometer reading is 75cm of mercury.
• Manometer measure the pressure of a tank as 250 cm of Hg. For the density of Hg 13.6 × 103 Kg/m3 and atmospheric pressure 101 KPa, calculate the tank pressure in MPa.
• A battery is well insulated while being charged by 12.3 V at a current of 6 A. Take the battery as a control mass and find the instantaneous rate of work and the total work done over 4 hours.