Atmospheric pressure at sea level – choose the most precise SI value\nWhich of the following best states the standard atmospheric pressure at mean sea level in SI units?

Introduction / Context:
Standard atmosphere (1 atm) is a reference pressure used in many engineering calculations. It has several equivalent representations, but SI practice prefers expressing it in kilonewtons per square meter or kilopascals.

Given Data / Assumptions:

• Standard atmosphere at sea level, 0 °C, approximate standard conditions.
• Equivalences: 1 atm ≈ 101.325 kPa ≈ 10.33 m of water ≈ 760 mmHg at 0 °C.

Concept / Approach:
The most precise SI representation among the options is 101.3 kN/m^2 (i.e., 101.3 kPa). Head of water and mmHg are convenient equivalents but not SI base pressure units, and “103 kN/m^2” is an overestimate.

Step-by-Step Reasoning:

Verification / Alternative check:
Converting 760 mmHg to SI pressure gives approximately 101.325 kPa using ρ_Hg ≈ 13,600 kg/m^3 and g ≈ 9.81 m/s^2.

Why Other Options Are Wrong:

• 10.3 m of water and 760 mm of mercury are correct equivalences but are not SI pressure units; the question asks for the best SI value.
• 103 kN/m^2 is a rounded-up value and not the standard.

Common Pitfalls:
Mixing head units (length) with pressure units; always choose kPa or kN/m^2 for SI pressure unless specifically asked for head.

Final Answer:
101.3 kN/m^2