Question

why the weight of same bag is more in pole than equator?

Answer 1

at the poles, the radius of the earth is smaller than the radius of the earth at the equator.
\[a = GM/r^2\]

here, G and M are constants So, acceleration and the square of the radius are inversely proportional. as radius decreases, acceleration incerases and thus, weight increases

Answer 2

There is a second reason: as Earth is rotating, the bag is subject to a centripetal force at the equator. There is no such force at the poles.