I'm stumped:

So bringing it back to the top. Hope that's ok!

2 charges, Q1 and Q2, equal magnitude, but different signs (not assigned) lie on a line, x axis, a known distance apart.

Segment p-q lies centrally on the line, distance apart is known.

An electron is released at p from rest, and passes q at a given time later. The field at the central segment pq is constant.(it's a short segment)

My job is to find the size and sign of Q1 and Q2 on this info.

I believe i can calculate the electrical force on the electron, but where next? Thanks