Question

explain why the value of g is zero at the centre of the earth

Answer 1

because low atmospheric air and no gravity at the centre of the earth and if a person goes in the centre of the earth again it can't come

Answer 2

if you see it in prospective of Newton so it is because as you will go towards the center of earth then gravity increase and as you will go opposite of it so it decrease as it follows the inverse square law so as going into centre where the origin of earths gravity starts as earth whole mass is there so in the origin there is no gravity by the universal law of gravitation formula you would see when you solve it.it comes like these
F=Gm1m2/r2
so there is no radius so it would be zero
but in the prospective of Einstein it would be like these that the curvature of space would be in starting

but according to me there must also be some gravity little but must because the mechanics of Einstein is correct and according to that it violates it that there is no gravity