Apressurized 2-m-diameter tank of water has a 10-cm-diameter orifice at the bottom where water discharges to the atmosphere. the water level initially is 3 m above the outlet. the tank air pressure above the water level is maintained at 450 kpa absolute and the atmospheric pressure is 100 kpa neglecting frictional effects, determine: (a) how long it will take for half of the water in the tank to be discharged; (b) the water level in the tank after 10 s

To save energy, the air supply to a 2000 ft office has been shut off overnight and the room temperature has dropped to 40°f. in the morning, the thermostat is reset to 70°f and warm air at 120 f begins to flov in at 200ft'/min. the air is well mixed within the room, and an equal mass flow of air at room temperature (changing with time) is withdrawn through a return duct. the air pressure is nearly 1 atm everywhere. ignoring heat transfer with the surroundings and kinetic and potential energy effects, estimate how long it takes for the room temperature to reach 70°f. plot the room temperature as a function of time.