00:01
Okay, for this problem we are told we have an object tossed upward and we're giving an equation that represents the flight of the ball.
00:12
So let's see.
00:14
For this problem, the most important fact that we know, always write down what you know.
00:18
We know that the height is represented by negative 16t squared plus 104t.
00:30
And what we want to know is the time at which the ball hits the ground.
00:38
So find the time at which the object returns to the point of departure.
00:41
So we're going to assume that the departure means it's starting from the ground or from basically h equals zero.
00:47
So we want to know the time at height equals to zero when it returns to zero.
00:55
So our plan is just basically to put in zero for our height and then solve this quadratic equation.
01:01
So we're going to do what we're going to put in zero for the height.
01:04
Negative 16 t squared plus 104t.
01:09
And i always try to factor first if i can.
01:11
It looks like we have some numbers that are factorable.
01:14
16 does not go into 104, but 8 divides evenly into 104.
01:19
So what i'm going to do here is pull out this negative 8t.
01:23
That's going to leave me with a 2t plus.
01:27
And then 104 divided by 8 is 13...