00:01
For number 35, there's a merry -go -round that has a diameter of 5 meters, and it has, it's slowing down.
00:09
And when it starts, it has a period of 4 seconds, and it takes 20 seconds to stop spinning.
00:24
So the final, i mean, the angular, the final angular velocity is 0, and we're asked to find how many revolutions it makes.
00:34
But first of all in part a where i's to find what would be the speed of something that is on the outer edge.
00:45
So that's just a linear velocity.
00:47
That's just a velocity equals a distance over time and the distance would be one time around two by r circumference and the radius r would be half of the diameter so it's 2 .5 and the time to go one time around is four seconds because that's what period means.
01:09
So i get a linear velocity of 3 .93 meters per second.
01:16
And then in part b, we're to find how many revolutions it makes.
01:22
Well, it started at this speed.
01:24
It started with a period of four.
01:25
So the initial angular velocity was one time around every four seconds.
01:33
So one time around is 2 pi radians per 4 seconds...