1. A particle (mass = 6.7 x 10-27 kg, charge = 3.2 × 10-19 C) moves along the positive x axis with a speed of 4.8 × 105 m/s. It enters a region of uniform electric field parallel to its motion and comes to rest after moving 2.0 m into the field. What is the magnitude of the electric field? 2. What is the speed of a proton that has been accelerated from rest through a potential difference of 4.0 kV? 3. If a 30 cm, b=20 cm, q = +2.0 nC, and Q=-3.0 nC in the figure, what is the potential difference VA - VB? A b B a