JAMB - Physics (1979 - No. 4)
Two closed vessels contain equal volumes of boiling water and are identical except that one is blackened on the outside while the other is polished. Which of the following is correct?
the polished vessel will cool faster because a polished surface is a good radiator
the polished vessel will cool faster because it will absorbe less heat from the room
the black vessel will cool faster because it is a better conductor of heat
the polished vesselwill cool faster because it reflects heat better
the black vessel will cool faster because a black surface radiates heat faster than a polished one
Shpjegimi
Black objects heat up faster than shiny ones, but they cool down faster too.