Oil spilled from a ruptured tanker is spreading in a circular pattern. If the radius of the circle is
increasing at the constant rate of 1.5 feet per second, how fast is the area of the spill increasing when
the radius of the spill is 42 feet?

Question

Oil spilled from a ruptured tanker is spreading in a circular pattern. If the radius of the circle is
increasing at the constant rate of 1.5 feet per second, how fast is the area of the spill increasing when
the radius of the spill is 42 feet?

goformit100 · Answer

use speed time formula...

anonymous · Answer

I've never heard of that.

anonymous · Answer

related rates right?

anonymous · Answer

Yeah, related rates.

anonymous · Answer

$A=\pi r^2$ and so $A'=2\pi rr'$

anonymous · Answer

you are told $r'=1.5$ and $r=42$
plug in the numbers and get $A'$ in one step

anonymous · Answer

wow, that was easy. I'm terrible at these.

goformit100 · Answer

@bloodrain

anonymous · Answer

yeah, i have to admit that one was real easy
they get harder

anonymous · Answer

:(

anonymous · Answer

well only the formulas get harder to figure out,
i am willing to bet that you knew the formula for the area of a circle

anonymous · Answer

yeah, I was just thinking like A=pi(r^t/1.5)^2 then I was super confused

anonymous · Answer

That made absolutely no sense to me.

anonymous · Answer

The minute hand on a watch is 8mm long and the hour hand is 4 mm long. How
fast is the distance between the tips of the hands changing at one o'clock?

THat's the hardest one I have done myself.