If gravity was the only force present would gravity, beside pulling, also stop the rotation / spin of a small object its pulling towards it over time? What would be the effect on an uneven object and what would be the effect on a perfect sphere?
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Related: https://physics.stackexchange.com/q/8074/2451 and links therein. – Qmechanic Jul 19 '18 at 17:51
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I assume you are talking about two interacting bodies orbiting about one another, one of which at least is asymmetric. Gravity would stop the self rotation by tidal forces, such as cause the tides on Earth. This would convert rotational energy into heat leading ultimately to body or bodies rotating with the same frequency as the orbital motion. The timescale over which this takes place depends on the nature of the bodies - soft/hard , large/small. For example the Earth's moon is in a rotationally locked state.
my2cts
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The gravity acting on a body, spherical or not, is, by definition, equivalent to a single force applied to the center of gravity (and, therefore, mass) of that body, which means that it won't produce any torque relative to the com and, therefore, won't cause any angular acceleration.
Hence, the gravity should have no effect on the rotation of the body.
V.F.
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Doesn't this conflict with the existence of tidal forces and the phenomenon of tidal locking? – probably_someone Jul 19 '18 at 18:44
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@probably_someone The question specifies "a small object", so tidal locking, which, according to Wikipedia, "arises from gravitational gradient", is hardly applicable.. – V.F. Jul 19 '18 at 19:02
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Depends on what "small" means. The Earth is pretty miniscule compared to the Sun, and yet there are still measurable tidal forces from the Sun. – probably_someone Jul 19 '18 at 19:04
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@probably_someone There was probably a reason the PO has specified a small object, but who knows. In any case, thanks for your comment - it definitely improves the answer. – V.F. Jul 19 '18 at 19:09