The diffusion coefficients for a maxwellian field star distribution depend on the functions g(x) and erf(x)- g(x), where g(x) is defined by equation (7.93) and x = v/(v20). show that g(x lim x0 x erf(x lim x-0 2 2 (7.218) 3/t x thus show that as the velocity of the subject star v + 0, the diffusion coefficients of equation (7.92) satisfy d[(avj|)2] = d[(av1)2]. explain physically why this must be so.

Consider a small frictionless puck perched at the top of a fixed sphere of radius r. if the puck is given a tiny nudge so that it begins to slide down, through what vertical height will it descend before it leaves the surface of the sphere? [hint: use conservation of energy to find the puck's speed as a func e conservation of energy to find the puck's speed as a function of its height at what value of this normal force does the puck leave the sphere? ] here on the puck.