Question

why an tub of steel floats on water

Answer 1

Because the air is filled in the tub n the density of steel decreases....
The density of water increase or the bouant force acting on steel increase and density of steel n weight of steel decreases...
Thus it float on water...
hope it help u...

Answer 2

Because there is air fill inside the tub due to which steel tub have more surface area in compare of volume that's why density is less and it floats over the surface of water.
Same it is in the case of ships