Mrs. Duffus would often complain when Duffus left the door to the basement open. “The cool air from the basement makes the upstairs cold; close that door, Duffus!” she would rant. “It won’t do any such thing,” Duffus would reply and go on his way. Duffus was right, but why?
Answer
Hot air rises and cold air descends, so cool air from the basement wouldn’t rise and make upstairs rooms colder.
