Question

Two point charges +q=1 μC and −q=−1 μC with mass m=1 g are fixed at the positions ±r⃗ 0 with |r0|=1 m. The charges are released from rest at t=0. Find the time τ in seconds at which they collide.

Hint: Can you do it without integrating by using Kepler's laws?

Details and assumptions
k=1/4πϵ0=9×10^9 m/F