Question

Why
does a ship made up of iron floats but the solid block of iron sinks?

Answer 1

a ship made of iron floats whereas a solid block of iron sinks .This is because the volume of the ship is more because of the spaces in it.so the density of ship is greatly reduced whereas the solid block of iron has less volume so the density is more and the solid block sinks.
(note:density=mass/volume)

Answer 2

because the ship is occupying more space when compared to solid block. and the ship is constructed on the basis of buyoncy making it to float on water till the weight of ship is less than buyoncy. as we know that there is action of buyont force in water.