Riders in an amusement park ride shaped like a viking ship hung from a large pivot are rotated back and forth like a rigid pendulum. at each end of the swing the ship hangs motionless for a moment before the ship swings down under the influence of gravity. assume that this motionless point occurs when the bar connecting the pivot point and the ship is horizontal.

On a mild saturday morning while people are working inside, the furnace keeps the temperature inside the building at 23degreesc. at noon the furnace is turned off, and the people go home. the temperature outside is a constant 16degreesc for the rest of the afternoon. if the time constant for the building is 3 hr, when will the temperature inside the building reach 18degreesc? if some windows are left open and the time constant drops to 2 hr, when will the temperature inside reach 18degreesc?