A proton gun fires a proton from mid-way among two plates, A and B, which are separated by a distance of 71.0 cm; the proton at firts moves at a speed of 170.0 km/s toward plate B. Plate A is kept at zero potential, and plate B at a potential of 400.0 V. The proton will not reach plate B.
Where will it turn around? (Relative to Plate A)
Determine with what speed will it hit plate A?