00:01
In this problem, we want to find the angular acceleration at a point on a dvd given the angular acceleration at a different point with a given radius and given angular acceleration.
00:13
To solve this, the first thing that we want to do is rewrite our v in terms of our radius.
00:20
And we can do this using the equation for period.
00:23
Now this equation is t equals 2 pi over omega.
00:28
And since omega is equal to v over r, this can be written as 2 pi r over v.
00:36
Then that can just be rearranged.
00:39
We have 2 pi r over t, giving us an equation of our velocity at a given point in terms of the radius.
00:46
So alpha 1 can be rewritten as 4 pi squared r squared over t squared times r.
00:56
We can cancel out that r squared and that r down here.
00:59
To get 4 pi r1 over t squared...