Question

An object has a weight of 100 N on the surface of the Earth. If the object is moved to 2RE above the surface of the Earth, its weight is
25.0 N.

11.0 N.

0 N.

100 N.

Answer 1

Weight of the object is defined as

$W = mg$

here

m = mass of object

g = acceleration due to gravity

now at the surface of earth

$g = \frac{GM}{R_e^2}$

so given that

$mg = 100 N$

now when it is moved to distance 2Re from the surface so its distance from the center of earth will be given as Re + 2Re = 3Re

so acceleration due to gravity will be given as

$g' = \frac{GM}{(3R_e)^2} = \frac{GM}{9R_e^2}$

so now weight is given as

$W = m*\frac{g}{9}$

$W = \frac{100}{9} = 11.1 N$

so now weight will be 11 N