00:02
All right, here's a fun physics problem.
00:04
We've got a ball being thrown upward with the starting velocity of 40 feet per second.
00:11
And we have the equation that describes the height of the ball with time being 40t minus 16t squared.
00:19
And our goal is to find the average velocity.
00:22
And we're going to do this basically for different lengths of time.
00:30
And we're going to kind of compare and see what our average velocity is for the different time periods.
00:35
Okay, so in general, average velocity is just basically the displacement over time.
00:41
So it's basically going to be our final y time minus y at two seconds because we're interested to find we're going to use approximate the velocity, is the average velocity, but our starting point is always two seconds.
00:59
And then that's going to be over t minus two.
01:02
All right, so we can substitute in our equation 40t minus 16 t squared.
01:09
And then we've got to figure out what, why is that two? so that's 80 minus 16 times four.
01:16
So that ends up being 16.
01:18
So we're going to subtract 16 all over t minus 2.
01:24
Okay, so that's going to be what we use to plug in their values.
01:29
So our first t is 0 .5 seconds later...