Definition 5.10High School Physics · অধ্যায় 5 — Relative Motion
The ground frame (or laboratory frame) is attached to the Earth’s surface where the experiment happens. It is the right frame for everyday motion: falling objects, vehicles, sports, laboratory benches.
The geocentric frame is centred on the Earth but does not spin with it (its directions point to distant stars). It is the right frame for the Moon and for artificial satellites, which orbit the Earth as a whole and ignore its daily rotation.
The heliocentric frame is centred on the Sun, with directions again fixed on distant stars. It is the right frame for the planets: each then follows a simple, nearly circular orbit.
Three nested frames: the ground spins with the Earth, the geocentric frame rides with the Earth without spinning, the heliocentric frame watches the whole dance from the Sun.
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