00:01
Alright, so we have a stone that's thrown upward with an initial velocity of 24 meters per second.
00:09
And the first part we want to know are at height 13 meters.
00:16
What is the velocity of the stone? and because this height is 13 meters and we're starting at 0 or delta y is just y minus y is 0, which is 13 minus 0, which is just 13.
00:33
We also know that a equals minus g as always.
00:40
And so we're looking for v, so we can use this equation.
00:48
And we know v0, we know a, and we know delta y.
00:53
So that works out.
00:54
We can just plug in.
00:56
V squared is 24 squared minus, because it's minus g, 2 times 9 .8 times 13 meters.
01:11
And so our v squared is 321 .2.
01:16
And that means our v is 17 .9 meters per second.
01:22
And this can actually be plus or minus because we're taking the square root.
01:26
And that will be answered in the second part, y can be plus or minus.
01:31
So for the second part we want to know what time this happens...