Doubled Spheres

Using the arrow tool, move the slider for a to manipulate this applet. The following are all based on the variable a: -The radius of the small sphere is a -The radius of the large sphere is 2a -The volumes of the spheres are displayed dynamically on the left -Point D is a point (x,y) of (radius, volume) for the small sphere -Point E is a point (x,y) of (radius, volume) for the large sphere
1) What is the ratio of the volume of the large sphere to the volume of the small sphere when a=1? 2) Does that ratio change when you change a? 3) Compare the traced graphs of Points D and E. What are similarities? Differences?