One can set up a two-dimensional scattering theory, which could be applied to puck projectiles sliding on ice and colliding. the cross section would be the effective width of a target, and the differential cross section (d sigma/d theta) would give the number of projectile scattered in the angle d theta a) show that the two-dimensional analog to d sigma/d ohm = b/sin (theta) = b/sin (theta) |db/d theta| is d sigma/d theta = |db/d theta| b) now consider the scattering of a small projectile off a hard disk of radius r pinned down to the ice. find the differential cross section. c) now calculate the total scattering cross section. does your result make sense? explain.