Revolution=Circumference?

[yo4561]

Hi MP,

In all the Quant Companion guide, that says "If the wheel has a diameter of 4 feet, then the point travels at a rate of 3 x 4pie=12pie feet per second." I am a bit confused on what is being said in this sentence because the previous sentence "if a wheel spins at 3 revolutions per second, a point on the edge travels a distance equal to 3 circumferences per second" seems to refer to a different scenario. Any insights on what is being said would be greatly appreciated because I am not sure where the 3 is coming from nor the pie (in the 3 x 4pie)?

[esledge]

Hi MP,

In all the Quant Companion guide, that says "If the wheel has a diameter of 4 feet, then the point travels at a rate of 3 x 4pie=12pie feet per second." I am a bit confused on what is being said in this sentence because the previous sentence "if a wheel spins at 3 revolutions per second, a point on the edge travels a distance equal to 3 circumferences per second" seems to refer to a different scenario. Any insights on what is being said would be greatly appreciated because I am not sure where the 3 is coming from nor the pie (in the 3 x 4pie)?

There are two things happening here:
(1) 3 is coming from the given rate ("3 revolutions per second")
(2) pi is coming from the circumference formula (circumference = pi*diameter)

The title of this post is correct: 1 revolution = 1 circumference (of "translational" distance traveled by a point on the edge of the rotating wheel)