2) A rock is dropped in a pond. A ripple moves out at a rate of 4 inches per second. How fast is the area changing when the ripple is 48 inches across A = r2 3) Air is forced out of a balloon at a rate of 230in3 per second. How fast is the radius changing when the balloon is a 36 inches across V = 4/3 r3 4) Sand drips out of a conical funnel at a rate of 340in3 per second. How fast is the height changing when the radius at the top of the sand is 18 inches. The radius of the funnel is 4 times the height. V = 1/3 r2h