Example 2: Aball bounces back offearth. You are asked to solve this quantum mechanically assuming the earth is an infinitely hard sphere. Consider surface of carth as the origin implying (0)= and a linear potential eleswhere (i.e. V(x) = -mgx for x > 0). Which ofthe following iwave function is physically admis- sible for this problem (with k> 0): (a)v(r)= (b) w(x)= Ae ()(r)=-Axe (d) w(x)= Axe"i.