What force must be applied to lift a stone weighing 100 kg from the bottom of a reservoir

What force must be applied to lift a stone weighing 100 kg from the bottom of a reservoir, if an Archimedean force equal to 400 N acts on it under water?

To calculate the force that is necessary to lift a stone from the bottom of a reservoir, it is necessary to subtract the value of the Archimedes force from the value of the gravity force acting on the stone.

F = Ft – Fа, where Ft is the acting gravity: Ft = m * g, where m is the mass of the stone (m = 100 kg), g is the acceleration of gravity (g = 10 m / s2), Fа is the value of the Archimedes force (Fa = 400 N).

F = Ft – Fa = m * g – Fa = 100 * 10 – 400 = 1000 – 400 = 600 N.

Answer: To lift a stone from the bottom of a reservoir, you need to apply a force of 600 N.