A ball is thrown into a lake creating a circular ripple whos
     A ball is thrown into a lake, creating a circular ripple whose radius travels outward at a speed of 8 centimeters per second.  Complete the following l table.  Define a formula that gives the radius of the ripple, r, in centimeters, in terms of the varying number of seconds that have elapsed since the ball hit the water, t.  Define a function f that determines the area of the ripple, A, in square centimeters, in terms of the varying number of seconds that have elapsed since the ball hit the water, t  f(t) =   
  
  Solution
b) radius after t sec ,r =8t
c) area of ripple f(r)=r2
we have r =8t
so f(t)=(8t)2
f(t)= 64t2
f(t)=64 t2

