Question

why does an object float or sink when placed on the surface of water

Answer 1

the object which flow Over the surface of the water they have low density for e.g piece of wood and the object which sink they have more density than water for eg. iron nail.

Answer 2

The outside of an object is called itssurface. When more of the surface is touching the water, the object is more buoyant (BOY-ant), which means it floatsbetter. When an object floats, it pusheswater out of the way. That's called displacement.