Q. If speed of rotation of the earth increases, the weight of the body__:
Answer: decreases
Notes: The weight of a body on the earth is the amount of gravitational pull on it exerted by the earth. Similarly there is another force exerted on a body on earth, that is centrifugal force due to its rotation which tries to move the body away from the centre of the earth and its maximum at the equator as the velocity of rotation is maximum at the equator of the earth. The gravitational force is balanced by the centrifugal force. With the increase in the speed of rotation of the earth the body at the equator will come more under the influence of the centrifugal force and the weight of the body will seem to have decreased. It is estimated that if the earth rotated 17 times faster than now then weight of a body at the equator will measure zero. However there will not be any change in the weight of a body at any of the poles, since there would not by any change in the centrifugal force there due to increase or decrease in the rotational speed of the earth.