So the coefficient of friction multiplied by V, and the sum is equal to zero. Now, the question is what exactly is the mass displaced? How else can we represent the displaced mass of that fluid that is displaced by that particle? Well, from fluid dynamics, we know that the mass displaced is equal to. So the mass displaced or the mass of the fluid that is displaced by that object is equal to the product of the mass of that object multiplied by the ratio of the density of the fluid to the density of that object. So let's call it a particle.