Question

Mass of an object on the surface of earth
is 80 kg. It's mass at the centre of the
earth is
(A) zero
(B) 80 kg
(C) 800 N
(D) 13.33 kg​

Answer 1

Explanation:

Let r be the distance from center of earth where it weighs 40 kg.

W

surface

=

R

2

GMm

W

r

=

r

2

GMm

Since W

r

=

2

1

W

p

,

r=

2

R.

Hence the height of this point=r−R=

2

R−R=(

2

−1)R

Answer 2

The correct answer is A zero