Specific weight (unit weight) of a liquid: does it vary with location on Earth?

Introduction / Context:
Specific weight γ (also called unit weight) is defined as γ = ρ g. Unlike density ρ, which depends mainly on temperature and pressure, γ also depends on local gravitational acceleration g, which varies over Earth’s surface.

Given Data / Assumptions:

• Liquid of given density ρ at a fixed temperature.
• Local gravity g differs with latitude and elevation.
• No phase change or strong compressibility effects.

Concept / Approach:

Because γ = ρ g, variation in g (approximately 9.78–9.83 m/s^2 on Earth) translates to small but real differences in γ by location. Therefore, the specific weight is not strictly constant from place to place on Earth, even if ρ were held constant.

Step-by-Step Solution:

Verification / Alternative check:

Gravity models (e.g., WGS) publish spatial variations in g, confirming the conclusion.

Why Other Options Are Wrong:

(a) Incorrect because g is not constant. (b) true in spirit but vague compared to (c). (d) Speculative and irrelevant; γ would vary with gravity on other planets as well. (e) Redundant when (c) states the fact directly.

Common Pitfalls:

Confusing density (material property) with specific weight (depends on gravity as well).

Final Answer:

varies from place to place on the earth