Question

The force of attraction (A) between two objects, whose masses are fixed, varies inversely with the square of their distance of separation (d). The force of attraction between them is 2 units when the distance is 5 cm. What is the distance between the two two objects,if the attraction between them is 8 units?

Answer 1

According to Newton law of Gravitation the force of attraction between two bodies is give by F = G m1m2/r^2

where m1 and m2 are the masses and r is the distance between them

therefore, 2 = Gm1m2/5^2 = Gm1m2/25 .............1)

Now if, F = 8 units, then

8 = Gm1m2/r^2 .......................2)

Dividing 2) by 1) we get,

8/2 = 25/r^2

4 = 25/r^2

r^2 = 25/4

r = 5/2 = 2.5 cm Ans.