1) Friction is exerted between a surface and a contacting object. Derive an equation for us, the coefficient of static friction, in terms of O, the angle of elevation of an incline, and physical
constants.

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?