Why do Objects float/sink? In this video we are discussing the concept of buoyancy. Why do objects float on water or when they sink in water? In simple words, we can say that when an object is immersed in water: if force applied by water is greater than the weight of the object, the object will float. if force applied by water is less than weight of the object, the object will sink. jf force applied by water is equal to tge weight of the object, the object remain suspended in water. just like the fish remain in water they doesnot either sink or float on surface