You are balancing on a log, and a friend is trying to knock you off. he throws a ball at you. you can catch it, or you can let it bounce off you. which is more likely to topple you - catching the ball or letting it bounce off

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?