Question

2 bodies A and B of masses of 2kg and 4kg are kept 2m away from each other. where should a body of mass 1kg replaced so that gravitational force on this body due to A and B is 0.
Plz... I want it now.

Answer 1

Mass of body a is Ma=2kg

Mass of body b is Mb=4kg

Mass of body cis Mc=1kg

Separation between a and b=2m

Let the body C be placed at a distance d fron the body A,

The gravitational force between A and C,

FAC=GMaMc/d^2=G*2*1/d^2=2G/d^2......1

the gravitational force between B and C is 

FBC=GMbMc/d^2=G*4*1/(2-d)^2=4G/(2-d)^2

For body C the gravttatinal force =0

hence Fac=Fbc

2g/d^2=4G/(2-d)^2

(2-d)^2=2d^2

2-d=√2d

(√2+1)d=2

d=0.83m