This is a simulation of the effects of the forces acting on an object that is initially completely submerged in a fluid. The density of the object and density of the fluid can be adjusted with the sliders or input boxes. When you click the "Run" button you will see an animation showing the motion of the object after being released under water. When the block reaches an equilibrium, either floating or resting on the bottom of the tank, it stops moving. The Free Body Diagram on the left shows the forces acting on the object and how they change as the object moves. The actual speed and acceleration of the object as it moves through the fluid are not necessarily realistic - but in general, when the net force is bigger the acceleration will be bigger.
What factor determines if the object will float or sink? When the block is floating, how do the amounts of the block above and below the surface relate to the densities of the fluid and the object? Does changing the density of the object change the buoyant force on the object? Does changing the density of the fluid change the buoyant force on the object?