Time 0 sec: pi(0 in)^2 = 0 in^2

Time 1 sec: pi(1.5 in)^2 = 2.25 pi in^2

Time 2 sec: pi(2*1.5 in)^2 = 9 pi in^2

Time 3 sec: pi(3*1.5 in)^2 = 20.25 pi in^2

...

Time 60 sec: pi(60*1.5 in)^2 = ???

Are you seeing it?

One more thing. This is in in^2. You must convert to ft^2. Do you know how to do that? It is NOT simply dividing by 12.