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ashna
Determine the speed with which the earth would have to rotate on its axis so that a person on the equator would weight 3/5 as much as at the present.
You'll have to use centripetal force equation.
Essentially, you need to find that rotational speed such that the resultant acceleration (gravity minus centripetal) is 3/5 of gravity alone.
Get handy the centripetal force formula, Newton's law of gravitation formula, and relevant data such as mass and radius of the Earth, and you'll be able to algebra your way through it.