Terminology – specific weight (weight density) “The specific weight of a fluid is also called weight density.” Decide whether this statement is:

Introduction:
Fluid properties have multiple names across unit systems and industries. This question checks the equivalence of two common terms for the same quantity.

Given Data / Assumptions:

• Specific weight γ is defined as weight per unit volume.
• Gravity is treated as uniform.
• Units may be N/m^3 (S.I.) or lbf/ft^3 (U.S. customary).

Concept / Approach:
Specific weight γ = ρ * g expresses how much weight a given volume of fluid possesses in a gravitational field. The term “weight density” is a synonym that emphasizes “weight per volume,” in contrast to mass density ρ (mass per volume).

Step-by-Step Solution:
1) Write γ = W / V.2) Relate W to mass m via W = m * g and m = ρ * V.3) Substitute to obtain γ = ρ * g.4) Therefore, “specific weight” and “weight density” refer to the same physical quantity.

Verification / Alternative check:
For fresh water near room temperature, ρ ≈ 1000 kg/m^3, so γ ≈ 9.81 kN/m^3; both terms are used interchangeably in handbooks.

Why Other Options Are Wrong:

• “Incorrect” and conditional versions contradict the definition; the equality is unit-agnostic.
• Claiming weight is not used is incorrect; engineering often uses weight-based units and heads.

Common Pitfalls:
Confusing mass density (ρ) with weight density (γ); they differ by g.

Final Answer:
Correct