when we move from the poles to the equator. hence,the value of g(grams) decreases. why?

The variation in value of acceleration due to gravity at a place on earth due to rotation of the earth is dependent on the distance of the place from the axis of rotation.

Let the g' = apparent value of acceleration due to gravity and g be the true value of acceleration due to gravity, ω = angular velocity of earth due to rotation of earth. R = distance of the place from the axis of rotation, then value of g' at the equator of the earth is given by,

At the equator, R is also the radius of the earth.

At poles, R is minimum or simply zero. Since, the axis of rotation passes through the poles. So, there is no effect of the rotational motion of the earth on the value of ‘g’ at the poles.

Thus at the equator, the weight is, mg^/ = mg – mω²R

And at the poles the weight is, mg^/ = mg

So clearly, weight is more at the poles than at the equator.

The mass of the object remains constant everywhere.