= Gravitational mass
{title2=$m_{\rm g}$}
Passive gravitational <mass> is the coefficient in $\mathbf F=m_{\rm g}\mathbf g$ for an imposed <Newtonian gravitational field>. Active gravitational <mass> instead measures a body's contribution to the source of that field in <Newton's law of universal gravitation>. Universality of the ratio of passive gravitational <mass> to <inertial mass> is the Newtonian content of the <weak equivalence principle>. In <general relativity>, the source is the full <stress-energy tensor>, rather than a single scalar gravitational <mass>.
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