Early Monday morning, the temperature in the lecture hall has fallen to 41 degrees F, the same as the temperature outside. At7:00, the janitor turns on the furnace with the thermostat set at 68 degrees F. The time constant for the building is 1/K = 3 hr and that for the building along with its heating system is 1/K1= 1/2 hr. Assuming that the outside temperature remains constant, what will be the temperature inside the lecture hall at 8:45 ?
When will the temperature inside the hall reach 67 degrees F?