Question 6
A ship made of metal floats on water while a solid block of the same metal sinks. Why?
The right answer is the one marked above.
The ship displaces a large volume of water, so the upthrust can equal its weight. The empty space enclosed by the hull is what lets it displace a volume far larger than the metal in it would on its own.
The metal is the same metal — the density has not changed. And the ship weighs far more than the block. The difference lies not in the weight but in the volume displaced.