What force must be applied to hold a piece of cork wood under water, which weighs 80 grams?

Given:

m = 80 grams = 0.08 kilograms is the mass of a piece of cork immersed in water;

ro1 = 113 kilograms per cubic meter – the density of balsa wood;

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

It is required to determine F (Newton) – what force must be applied to keep a piece of wood in water.

Find the volume that a piece of balsa wood occupies:

V = m / ro = 0.08 / 113 = 7 * 10-4 m3.

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

F = Farchimedes – F gravity;

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

F = g * (ro * V – m);

F = 10 * (1000 * 7 * 10-4 – 0.08) = 10 * (0.7 – 0.08) = 10 * 0.62 = 6.2 Newton.

Answer: To keep a piece of balsa wood in water, you need to apply a force equal to 6.2 Newtons.