The principle of floatation states that when an object floats in a liquid the buoyant force/upthrust that acts on the object is equal to the weight of the object.
As shown in the figure above, if the weight of the object (W) = upthrust (F), the object is in balance and therefore float on the surface of the fluid.
If the weight of the object > upthrust, the object will sink into the fluid.
Note
Displaced volume of fluid = volume of the object that immerse in the fluid.
If weight of the object > upthrust, the object will sink into the fluid.
If weight of the object = upthrust, the object is in balance and therefore float on the surface of the fluid.