Question

the weight of the body at a distance 2R from the of the earth of radius R is 2.5N.if the distance is 3R from the centre of the earth the weight of the body is?

Answer 1

The weight at a distance of 3R will be 1.11 N

From newton's law we know that the force of attraction due to gravity

F = $\frac{Gm1m2}{r^2}$

Where G = gravitational constant

m₁ = mass of earth

m₂ = mass of object

r = distance from the center of earth

Hence

weight ∝ 1/r²

=> w₁/w₂ = r₂²/r₁²

=> 2.5/w₂ = 9R²/4R² = 9/4

=> w₂ = 2.5 x 4/9

=> w₂ = 1.11 N

Hence the weight at a distance of 3R will be 1.11 N.