An employee is required to unload 30 cm cardboard cubes from a pallet (15 cm thickness) and place them on a conveyor that is 80 cm high. The cartoons are unloaded at 6 cartons per minute. Each pallet has one layer of cartons containing 16 cartons. The operation requires the worker to twist approximately 900 while turning to unload the cartoon on to the conveyor. A maximum of twelve pallets are unloaded during the first hour of each shift (the activity takes place only once per shift). Find the recommended weight limit for the activity.

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 the air is well mixed within the room, and an equal mass flow of air at room temperature (changing with time) is withdrawn through a return duct.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