A set of two forces that are in opposite directions, have equal magnitudes and act on different objects
Answer:

Explanation:
The total kinetic energy of both electrons will be electrostatic potential energy, when the electrons reach the minima distance due to electrostatic repulsion. Then, you have:

me: mass of the electron
q: charge of the electron
k: Coulomb's constant
you take into account that v2=3v1=3v and do rmin the subject of the formula:
![\frac{1}{2}m_e[v^2+9v^2]=5m_ev^2=k\frac{q^2}{r_{min}}\\\\r_{min}=\frac{kq^2}{5m_ev^2}](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7B2%7Dm_e%5Bv%5E2%2B9v%5E2%5D%3D5m_ev%5E2%3Dk%5Cfrac%7Bq%5E2%7D%7Br_%7Bmin%7D%7D%5C%5C%5C%5Cr_%7Bmin%7D%3D%5Cfrac%7Bkq%5E2%7D%7B5m_ev%5E2%7D)