JAMB - Physics (1982 - No. 16)
Why does a piece of cork float on water?
there is no upthrust on it when completely immersed in water
the upthrust on it when completely immersed in water is greater than its weight in air
the upthrust on it when completely immersed in water is less than its weight in air
its specific gravity is greater than that of water
its specific gravity is the same as that of water
Vysvetlenie
It floats because it weighs more than amount of water it would have to push out of the glass if it sank. This means, its weight in air is less than its upthrust.