Experiment: Each platform on the tower is 5 meters higher than the one below it. Drop the ping pong ball from the lowest (5 meter) platform, then the next platform (10 m) and so on. What is the terminal velocity of the ping pong ball?​

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?