Gravitational field
A region of space where a massive object exerts a gravitational force on any other mass. Gravitational field strength g is the gravitational force per unit mass: g = F/m, measured in N/kg or m/s². Near Earth's surface, g ≈ 9.81 m/s² directed downward. The gravitational field is radial around a point mass or uniform spherical mass.
Formula
g = F/m (N/kg); g = GM/r²
Real World
NASA's Mars rovers are designed around Mars's surface gravitational field strength of ~3.7 N/kg, meaning engineers can use heavier scientific instruments than an equivalent Moon mission.
Exam Focus
Distinguish g as field strength (N/kg) from g as acceleration (m/s²) — they are numerically equal but conceptually different; state which context you mean.
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