Solve the following :
Question:

The gravitational force acting on a particle of $1 \mathrm{~g}$ due to a similar particle is equal to $6.67 \times 10^{-11} \mathrm{~N}$. Calculate the separation between the particles.

Solution:

$F=\frac{G m_{1} m_{2}}{r^{2}}$

$6.67 \times 10^{-17}=\frac{6.67 \times 10-11 \times \frac{1}{1000} \times \frac{1}{1000}}{x^{2}}$

$r^{2}=\frac{6.67 \times 10-17}{6.67 \times 10-17}$

$r=1 \mathrm{~m} .$