Question

Gravitational force between two point masses $m$ and $M$ separated by a distance $r$ is $F$. now if a point mass $3m$ is placed very next to m, the total force on $M$ will be

• A. $F$
• B. $2F$
• C. $3F$
• D. $4F$

Answer 1

The correct option is D $4F$

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

Force on M would be,

$\frac{GMm}{r^2}+\frac{GM\left(3m\right)}{r^2}$

$=\frac{4GMm}{r^2}=4F$