What force must be applied to keep a ball with a mass of 12 kg and a volume of 3 dm3 in water.

Given:

m = 12 kilograms is the mass of some ball immersed in water;

V = 3 cubic decimeters – the volume of the ball;

ro = 1000 kilograms per cubic meter – the density of water.

It is required to determine F (Newton) – what force must be applied to the ball to keep it in the water.

Let’s translate the units of measurement of volume in the SI system:

V = 3 dm3 = 3 * 10-3 = 3/1000 = 0.003 m3.

Then, to determine the strength, you must use the following formula:

F = F gravity – Farchimedes;

F = m * g – ro * V * g, where g = 10 Newton / kilogram (approximate value);

F = g * (m – ro * V);

F = 10 * (12 – 1000 * 0.003) = 10 * (12 – 3) = 10 * 9 = 90 Newtons.

Answer: to keep the ball in the water, you need to apply a force equal to 90 Newtons.