Problem data: m (mass of the considered plug) = 2 g (in SI system m = 2 * 10-3 kg).
Constants: g (acceleration due to gravity) ≈ 10 m / s2; ρw (water density) = 1000 kg / m3; according to the condition ρp (plug density) = 0.2 g / cm3 (in SI system ρp = 200 kg / m3).
The force required for complete immersion of the test tube in water is calculated by the formula: F = Fa – Ft = ρw * g * V – m * g = ρw * g * m / ρp – m * g = (ρw / ρp – 1) * m * g.
Calculation: F = (1000/200 – 1) * 2 * 10-3 * 10 = 0.08 N.
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