How fast is the snowball melting ? A spherical snowball initially has a 60 cin radius and it is melting . If the radius shrinks at a constant rate of 2 cm per minute , how fast is the volume of the snowball shrinking ? A spherical snowball initially has a 60 cm radius and it is melting . If the radius is shrinking at 2 cm per minute when ! = 20 cm , how fast is the volume of the snowball then shrinking ? Compare these two solutions . When is rate - of - change of the radius over all time useful to know and when is rate - of - change of the radius at a specific moment all that is needed