Measuring arc length

Move the green point so that the central angle is 1 radian. What is the length of the intercepted arc (in feet)?

Move the green point so that the central angle is 2 radians. Now what is the length of the intercepted arc in feet?

What is the relationship between the length of the arc (s), the measure of its corresponding central angle (use to represent a general central angle), and the radius of the circle (r)? We want an equation for s: s=???

What would be the central angle that cuts off an intercepted arc of length = 16 ft? Move the green point to check your answer. Explain why this is the case.