00:01
So in this video, we'll be discussing problem 13, 15, and 16, which all deal with position functions.
00:13
In the first case, we're looking at a rock, though, which is going to reach a height of s equals 24t minus 0 .8t squared.
00:26
And what we recognize is that we could look at this graphically and see, okay, this is the maximum height, all that.
00:31
Another option, though, that we have is to find the maximum height, we consider when the velocity is equal to zero.
00:38
Well, if we take the derivative, we know that the velocity is going to be 24 minus 1 .6t.
00:44
So if we set this equal to zero, what we end up getting is 24 over 1 .6 is the time.
00:52
So 15 seconds is when it reaches the maximum height...