g Explain why the foil is attracted at first by the charged rod. Consider any charge that exists in the uncharged foil. (You will consider later interaction between the rod and foil in the last question. Just think about the first interaction when answering this question.) [4] (Hint: It might help to recall that aluminum is a metal so charge in it can move. You will have to think about the interaction between any charge that has separated in the aluminum and the charge on the charged rod.)

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?