At what rate the earth should rotate so that the weight of a body at the equator of the earth becomes zero?

If the distance between the two particle is increased by 2% then the force of attraction between them will

If the radius of earth decreases by 10% the mass remaining unchanged.What will happen to the acceleration due to gravity

The ratio of energy required to raise a satellite upto a height h above the earth from earth surface to that required to put in to orbit there from that height is