Speed of a proton??? i just don't know where to start with this??? do i have to go back to basic physics?? i tried using the charge of the single proton to find the force of the electric field, and then with that force find an acceleration maybe??? im way confused A uniform electric field has a magnitude of 2.8 103 N/C. In a vacuum, a proton begins with a speed of 2.1 104 m/s and moves in the direction of this field. Find the speed of the proton after it has moved a distance of 1.0 mm. your help would be greatly appreciated!