when an object is immwersed in a liquid, it displaces a certain amount of liquid(whose volume is equal to the vo;lume of the immersed part of the object). that liquid exerts an upthrust on the object inthe given direction as shown.
So when an object is immersed in a liquid, two forces act on it:
1. weight of the object which acts downwards say W1=Vdsg ds is density of solid,V=volume of solid
2. upthrust which acts upwards say w2=vdlg dl is density of liquid, v=volume of solid which is inside liquid.
ifw1>w2 then the object sinks
ifw1<w2 then the object floats
w1=w2 then the object floats inside liquid