Gas is escaping from a spherical balloon at a constant rate of 2 fˆ3/min. How fast is the outer surface area shrinking?

Problem
Gas is escaping from a spherical balloon at a constant rate of 2 ft3/min. How fast, in ft2/min, is the outer surface area of the balloon shrinking when the radius is 12 ft?

A.   1/2 C.   1/3
B.   1/5 D.   1/4

 

Volume of Inflating Spherical Balloon as a Function of Time

Problem
A meteorologist is inflating a spherical balloon with a helium gas. If the radius of a balloon is changing at a rate of 1.5 cm/sec., express the volume V of the balloon as a function of time t (in seconds). Hint: Use composite function relationship Vsphere = 4/3 πr3 as a function of x (radius), and x (radius) as a function of t (time).

A.   V(t) = 5/2 πt3 C.   V(t) = 9/2 πt3
B.   V(t) = 7/2 πt3 D.   V(t) = 3/2 πt3