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=Vd_sg   d_{s is density of solid,V=volume of solid}

2. upthrust which acts upwards say w2=vd_lg   d_{l is density of liquid, v=volume of solid which is inside liquid.} 

ifw1>w2 then the object sinks

ifw1

w1=w2 then the object floats inside liquid