On a cold (5F) day 30 gallon per minute of water is being pumped from a well to a storage tank 100 ft above the level of the water in the well. The temperature of the well water is 350 F. Although the storage tank and water lines are insulated, they still loose 5000 Btu/hr to air. To avoid having the water freeze, a heater puts 1000 Btu/min into the water line. The motor that operates the water pump is 5 hp and 30% efficient, i. e. 30% of the energy goes into the water and the rest is dissipated to the air. If the storage tank is initially empty, what is the temperature of the water in the tank after one hour. Assume that the storage tank is vented to the atmosphere.

Amass of 1.5 kg of air at 120 kpa and 24°c is contained in a gas-tight, frictionless piston-cylinder device. the air is now compressed to a final pressure of 720 kpa. during the process, heat is transferred from the air such that the temperature inside the cylinder remains constant. calculate the boundary work input during this process.

Amass of m 1.5 kg of steam is contained in a closed rigid container. initially the pressure and temperature of the steam are: p 1.5 mpa and t 240°c (superheated state), respectively. then the temperature drops to t2= 100°c as the result of heat transfer to the surroundings. determine: a) quality of the steam at the end of the process, b) heat transfer with the surroundings. for: p1.5 mpa and t 240°c: enthalpy of superheated vapour is 2900 kj/kg, specific volume of superheated vapour is 0. 1483 m/kg, while for t 100°c: enthalpy of saturated liquid water is 419kj/kg, specific volume of saturated liquid water is 0.001043m/kg, enthalpy of saturated vapour is 2676 kj/kg, specific volume of saturated vapour is 1.672 m/kg and pressure is 0.1 mpa.

The y form of iron is known as: a) ferrite b) cementite c) perlite d) austenite