Question

when will an object sink or float

Answer 1

Hey,
Ur answer is here,
Case 2,
W=U
In this case block is floating with the whole of the block being just inside the liquid.
Weight of liquid displaced is equal to weight of block.
Case 3,
W>U
In this object has sunk to the bottom of the vessel. The weight of liquid displaced is lesser than the weight of block.
Hope it helps you ☺️

Answer 2

Whether an object sinks or floats, it depends on the density. But it does not depend on weight of the objects.

=>An object will float if it has less density than the liquid it is placed in.

=>An object will sink if it has more density than the liquid it is placed in.

Hope it helps