00:01
Okay, so we've got a kinematics problem where there's some water rising to a maximum height and then falling back down.
00:07
And we want to know the height of the geyser and the initial speed of the water.
00:12
Now, they don't give you any numbers here.
00:14
They just give you some symbols.
00:16
So we know that the time is t.
00:20
That's going to be considered a known value.
00:22
We know that the acceleration is downward, acceleration due to gravity, so negative g or negative 9 .8.
00:29
And then if it's reaching a maximum height, the final velocity is going to be zero.
00:34
So these are our three known quantities.
00:38
For part a, what's the height of the geyser? that's going to be delta y.
00:42
And for part b, we're looking for the initial velocities.
00:46
We've got to find both of these.
00:47
I would actually argue that getting part b is going to be the easier one to do first.
00:51
So let's do part v first and come back to part a here.
00:55
We need an equation with vi, vf, a, and t.
00:58
That equation is going to be this one.
01:01
Vf is equal to vi plus a .t.
01:05
And the final velocity is zero.
01:09
So i can subtract over vi.
01:13
And you know what? let's actually take a step back here.
01:15
Let's just plug in some numbers on this.
01:20
So i'm going to have zero is equal to vi.
01:25
And then the acceleration is negative g times t...