I feel like I shouldn't have to say this, but I want everyone to understand. (If you do GREAT <3) Don't join people's Zooms. There is a guy going around asking people to Zoom, (look out for the code: 825 338 1513) then when they get on, he asks them to show their bodies/other innapropriate things. His name on Zoom is "Mysterious Men" Please stay safe guys, these are strangers, not your friends. If you can, repost this. If you feel the need, report this question. I just want to raise some awareness. 1

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 the air is well mixed within the room, and an equal mass flow of air at room temperature (changing with time) is withdrawn through a return duct.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.