The radius of a circular oil slick expands at a rate of 8 m/min.

Question

a. How fast is the area of the oil slick increasing when the radius is 30 m? = 480pi

b.If the radius is 0 at time t=0 , how fast is the area increasing after 2 mins?

i cannot get part b!

Answer 1

At a rate of 8 m/min, after 2 minutes the radius will be 16 m.

Now sub r=16 into your dA/dt you had in a)