Calculating Change in Volume of a Shrinking Sphere

[Qube]

Homework Statement

http://i.minus.com/jbxIzu0P7sTqP0.png

Homework Equations

V(sphere) = 4/3(pi)(r^3)

V = 36pi in^3

dr = -0.2 in

dV = ?

The Attempt at a Solution

I basically solved for the radius, and took the derivative and plugged in the value of the radius and the change in the radius to get the change in the volume.

http://i.minus.com/jbsA5BJkMOPHgl.jpg

Also upon further consideration it appears that one can easily eliminate the answers that claim the volume increases since that wouldn't make any geometric sense; if the radius was shrinking one would naturally expect the volume of a sphere to follow suit.

 

[verty]

I see no question here.

 

[Mark44]

Homework Statement

http://i.minus.com/jbxIzu0P7sTqP0.png

Homework Equations

V(sphere) = 4/3(pi)(r^3)

V = 36pi in^3

dr = -0.2 in

dV = ?

The Attempt at a Solution

I basically solved for the radius, and took the derivative and plugged in the value of the radius and the change in the radius to get the change in the volume.

http://i.minus.com/jbsA5BJkMOPHgl.jpg

Also upon further consideration it appears that one can easily eliminate the answers that claim the volume increases since that wouldn't make any geometric sense; if the radius was shrinking one would naturally expect the volume of a sphere to follow suit.

Looks good!