Answer:
210nC
Explanation:
The force experimented by two charges [tex]q_1[/tex] and [tex]q_2[/tex] separated a distance [tex]r[/tex] is given by Coulomb's Law:
[tex]F=\frac{kq_1q_2}{r^2}[/tex]
where [tex]k=9\times10^9Nm^2/C^2[/tex] is the Coulomb constant.
The acceleration experimented by any (both) of them will be given by Newton's 2nd Law: F=ma
Combining both equations and considering that [tex]q_1=q_2=q[/tex], we get:
[tex]ma=\frac{kq^2}{r^2}[/tex]
Which means:
[tex]q=\sqrt{\frac{mar^2}{k}}[/tex]
Which for our values is:
[tex]q=\sqrt{\frac{(0.001kg)(980m/s^2)(0.02m)^2}{9\times10^9Nm^2/C^2}}=2.09\times10^{-7}C=209\times10^{-9}C=209nC[/tex]
Which is very close to the option 210nC
