00:01
We have a person which is standing on the edge of a cliff, and they throw an object into the air, originally at 18 meters per second, and it's going to come back down, and we're told the cliff is 15 meters in the air.
00:14
So for a, we want to solve for the time it takes for the entire trip, which i'm going to use velocity final equals velocity initial, plus acceleration times time.
00:23
But first, i need to find our final velocity.
00:25
And so we're actually going to be answering b first.
00:28
So i'm going to use final velocity squared is equal to initial velocity squared plus two times acceleration times displacement.
00:35
So our initial velocity is 18 and this is squared plus two times negative 9 .8 times its displacement.
00:44
And so its displacement really is just this portion, which is negative 15.
00:50
And so when we do this, we get final velocity squared is equal to 618...