A ball has a diameter of 3.79 cm and average density of 0.0838 g/cm3.

What force is required to hold it completely submerged under water?

Answer: 0.258 N

Explanation:

As the density of the object is much less than the density of water, it's clear that the buoyant force, is greater than the weight of the object, which means that in normal conditions, it would float in water.

So, in order to get the ball submerged in water, we need to add a downward force, that add to the weight, in order to compensate the buoyant force, as follows:

F = Fb - Fg

Fb = δH20 * 4/3*π * (d/2) ³ * g

Fg = δb * 4/3*π * (d/2) ³ * g

F = (δH20 - δb) * 4/3*π * (d/2) ³*g

Replacing by the values of the densities, and the ball diameter, we finally get:

F = 0.258 N