An iron nall sinks in water. While a large ship floats on the surface of water. Give reason.

This floats on water

Iron nail sinks in water. Empty iron tin box floats on water. why?

Seeds that float on water

A cube with a mass m = 20g wettable by water floats on the surface of water. Each face of the cube is a = 3cm long. Surface tension of water is 70 dyne/cm. The distance of the lower face of the cube from the surface of water is (x+0.3)cm. Find x. (g = 980cm/ s^2 )