A piece of granite with a volume of 10 dm3 is submerged in water. What force must be applied to keep it in the water?

Data: V (volume of a piece of granite taken) = 10 dm3 (in SI system V = 0.01 m3).

Reference values: g (acceleration due to gravity) ≈ 10 m / s2; according to the condition ρw (water density) = 1000 kg / m3; ρg (density of granite) = 2600 kg / m3.

The force applied to the taken piece of granite is calculated by the formula: F = Ft – Fa = m * g – ρw * g * V = ρg * V * g – ρw * g * V = V * g * (ρg – ρw).

Let’s make a calculation: F = 0.01 * 10 * (2600 – 1000) = 160 N.

Answer: A force of 160 N. must be applied to the taken piece of granite.