Answer: 49 N.
- A 49 N
- B 98 N
- C 0 N
- D 24.5 N
Correct answer: A. 49 N
Explanation: V = m/ρ = 10/2000 = 5×10⁻³ m³. F<sub>b</sub> = 1000 × 5×10⁻³ × 10 = 50 N. Weight = 10 × 10 = 100 N. Net downward = 100 - 50 = 50 N... Hmm let me recalculate: Weight = mg = 10 × 9.8 = 98 N. F<sub>b</sub> = ρ_w V g = 1000 × (10/2000) × 9.8 = 49 N. Net = 98 - 49 = 49 N.
Since the same volume of fluid must pass every cross-section per second (continuity), the fluid speeds up where the pipe narrows; Bernoulli's equation then says this faster-moving fluid has lower pressure - the principle behind a venturi meter and an aircraft wing's lift.
Concept context
Pressure, buoyancy, Bernoulli equation, viscosity, and surface tension.