Question

A body is lying on the surface of the earth. Suppose that the earth suddenly loses its power of attraction, then:
A) The weight of the body will become zero
B) The weight of the body will become infinite
C) The mass of the body will become zero
D) The body will vanish in air

Answer 1

Weight of a body is the force with which earth attracts any body towards its centre. So if the force of attraction becomes zero or the earth loses its power of attraction then the weight of the body will be null. There will not be any force which will attract the body. It will be considered as zero gravity. In zero gravity the body tends to move freely.

Complete step by step answer:
If the earth suddenly loses its power of attraction then the weight of the body will become zero. The weight of the body is given by $W = mg$ where $m$=mass of body and $g$=acceleration due to gravity. Since mass of the body can never be zero and mass is independent of the force of attraction by the earth. So the mass of the body does not become zero. Whereas if the force of attraction becomes zero then the acceleration produced due to force also becomes zero.

The relation between force and acceleration is given by $F = ma$. Here if the external force becomes zero then the acceleration becomes zero. And in turn the weight of the body becomes zero. The weight of the body is directly related to the force of gravity. And this force changes from planet to planet. More the mass of the planet more will be the force of gravity and more will be the weight. The weight of anybody on the moon is 1/6th of its weight on earth. Losing of force of attraction means losing gravity. And if gravity is zero that means the weight of the body is zero.

Note: The weight of the body is directly dependent on the gravity of a planet. So if gravity is zero that means the weight of the body is also zero. Whereas the mass of the body cannot be zero in any condition. So the body will not vanish. The mass is the total matter inside a body whereas the weight is the total force applied on the body by the planet.