(a) How rapidly is the area enclosed by the ripple increasing when the radius is 5 feet?

(b) How rapidly is the area enclosed by the ripple increasing at the end of 9.6 seconds?

Question:

# A stone dropped into a still pond sends out a circular ripple whose radius...

(a) How rapidly is the area enclosed by the ripple increasing when the radius is 5 feet?

(b) How rapidly is the area enclosed by the ripple increasing at the end of 9.6 seconds?