Question

How does weight of an object change on moving from equator to poles? When can the weight of an object be zero?

give answer for 2 marks and valid answer.

Answer 1

The weight of an object changes when the velocity of an object is comparable to velocity of light.
The weight of an object remains zero at the equator...

And this is enough for 2 marks dear..

Answer 2

w=mg
weight proportional to mass and gravity. gravity at equator is less than that at the poles. so you get different weight. The weight of an object is zero only when the gravitational force is zero.