Identify which physical quantity uses the unit kg/m^3 in the S.I. system.

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Solve this multiple-choice question and choose the correct option.

Accepted Answer

Introduction / Context:Recognizing units at a glance helps prevent dimensional mistakes in calculations. The unit kg/m^3 appears across materials, soils, fluids, and gases, making it one of the most frequently encountered units in mechanics and civil engineering. Given Data / Assumptions: Density is mass per unit volume. kg is the S.I. base unit of mass; m^3 is the S.I. unit of volume. Other listed quantities have different S.I. units. Concept / Approach:Match each physical quantity with its canonical S.I. unit: force → newton (N), volume → m^3, pressure → pascal (N/m^2), specific weight → N/m^3. Only density correctly matches kg/m^3. Step-by-Step Solution: Recall definition: density = mass / volume.Substitute S.I. units: mass → kg; volume → m^3 → density unit = kg/m^3.Check alternatives and eliminate mismatches. Verification / Alternative check: Use known values: water ≈ 1000 kg/m^3; concrete ≈ 2400 kg/m^3; air ≈ 1.2 kg/m^3. Why Other Options Are Wrong: Force: N; Volume: m^3; Pressure: N/m^2; Specific weight: N/m^3. Common Pitfalls: Confusing specific weight (weight per volume) with density (mass per volume).Misreading kg/m^3 as m^3/kg (specific volume). Final Answer: Density

Identify which physical quantity uses the unit kg/m^3 in the S.I. system.

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