7 ms·

I'm confused, I also immediately came to 3 when I read this question. Is that wrong? What's the correct answer?

• ryathal 5y ago
  the answer is 4. The reason it's 4 is because distance traveled is relative to the center of the circle. A circle will travel it's circumference in a rotation, but the distance traveled isn't actually the circumference of the inner circle, because that isn't where the center of the circle is. It actually travels the sum of the two circles radii.