00:01
So we know that the yo -yo is traveling at 4 ,500 revolutions per minute, and we know that it has a diameter of 2 .25 inches.
00:11
And we want to figure out the edge of, if we think of the yo -yo, this edge of it, how many miles per hour does it travel? so we know, first of all, one revolution is equivalent to 2 pi r, or pi times diameter.
00:33
So one revolution is two point two five times pi.
00:39
So the circumference or one revolution is 2 .25 times pi inches.
00:47
So we know that we are going 4 ,500 revolutions.
00:53
Well, let me move this down here.
00:54
We're going 4 ,500 revolutions per minute, one revolution is going 2 .25 high inches.
01:08
So right now our answer is in inches per minute.
01:13
But we don't want inches per minute.
01:15
We want miles per hour.
01:17
So let's change our inches...