Final theoretical check.
I. An astronaut inside an orbiting spacecraft is in a non-inertial frame of reference with respect to the Earth.
II. A plumb line in a satellite will hang horizontally.
III. If gravity suddenly disappears, a satellite would move tangentially to its orbit.
IV. Kepler’s third law (T² ∝ R³) is strictly valid only for circular orbits; for elliptical orbits, it is T² ∝ a³.
V. Two satellites of different masses in the same orbit have the same speed.
