= Solution
<inertial mass> sets the response to <force>, $\mathbf F=m_i\mathbf a$. Passive <gravitational mass> sets the response to a given <gravitational potential>, $\mathbf F_g=-m_g\nabla\Phi$; active <gravitational mass> describes a body's gravitational sourcing. Universality of the passive-to-inertial mass ratio makes freely falling trajectories independent of composition. <torsion balance> comparisons and differential free-fall experiments test this <weak equivalence principle> by searching for composition-dependent acceleration, with environmental <forces> and instrumental asymmetries controlled.
The <Einstein equivalence principle> further says that local nongravitational experiments in a freely falling laboratory obey <special relativity>, independent of the laboratory's location and <velocity>. A local inertial coordinate system can remove <Christoffel symbols> at one event, but cannot remove a nonzero <Riemann tensor> throughout a finite region. Relative acceleration of separated freely falling particles reveals tidal <gravity>. Thus a uniformly accelerating laboratory in flat <spacetime> can mimic a local gravitational field, while extended tidal measurements distinguish genuine curvature. Equality of the measured mass responses does not make every gravitational field globally equivalent to acceleration.
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