The mass of the marble slab is 40.5 kg. What force must be applied to it in order to lift it in the water?

Given:

m = 40.5 kilograms is the mass of the marble slab;

ro = 2700 kg / m3 (kilogram per cubic meter) – density of marble;

ro1 = 1000 kg / m3 – water density.

It is required to determine F (Newton) – what force must be applied to lift a marble slab in water.

Since the condition of the problem is not specified, we assume that the lifting of the slab will occur uniformly, that is, with a constant speed.

Let’s find the volume that the marble slab occupies:

V = m / ro = 40.5 / 2700 = 0.015 m3.

Then, according to Newton’s first law, we get:

F = F gravity – Farchimedes;

F = m * g – V * ro1 * g, where g = 10 Newton / kilogram (approximate value);

F = g * (m – V * ro1);

F = 10 * (40.5 – 0.015 * 1000) = 10 * (40.5 – 15) = 10 * 25.5 = 255 Newtons.

Answer: To lift a marble slab under water, you need to apply a force equal to 255 Newtons.