To determine the magnitude of the holding force acting on the specified plate, we apply the formula: Fр = Fт – Fa = m * g – ρw * g * V = ρb * V * g – ρw * g * V = V * g * (ρb – ρw ).
Constants and variables: V – slab volume (V = 4 m3); g – acceleration due to gravity (g ≈ 10 m / s2); ρb is the density of the slab, concrete (density of heavy concrete ρb = 2000 … 2500 kg / m3; we take ρb = 2250 kg / m3); ρw is the density of the water in which the indicated plate is immersed (ρw = 1000 kg / m3);
Calculation: F = V * g * (ρb – ρv) = 4 * 10 * (2250 – 1000) = 50 * 10 ^ 3 N.
Answer: To hold the indicated plate in water, a force of 50 kN is required.
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