Question

Three uniform spheres each having a mass M and radius a are kept in such a way that each touches the other two. Find the magnitude of the gravitational force on any of the spheres due to the other two.
A. `(Gm^(2))/(r^(2))`
B. `(Gm^(2))/(4r^(2))`
C. `sqrt(2)(Gm^(2))/(4r^(2))`
D. `sqrt(3)(Gm^(2))/(4r^(2))`

Answer 1

Correct Answer - D
The given system may be regarded as a system of three particles located at the three vertices of an equilateral triangle of side `2r`. Now, `F_(A)=F_(B)`
`=(Gm^(2))/((2r)^(2))=(Gm^(2))/(4r^(2))`
`F_(A)` and `F_(B)` are inclined to each at an angle of `60^(@)`. if `F` is the resultant of `F_(A)` and `F_(B)`, then
`F=sqrt(3)xx(Gm^(2))/(4r^(2))`