A student is conducting an experiment to determine how far a ballwill roll down a ramp based on the angle of incline what are the three possible controls for the experiment

Two 2.0-cm-diameter disks face each other, 1.0 mm apart. they are charged to ±10 nc. what is the electric field strength between the disks? a proton is shot from the negative disk toward the positive disk. what launch speed must the proton have to just barely reach the positive disk?