00:01
Okay, so we have a car wreck between three cars, and they're all sticking together, and we want to get the speed of the wreckage.
00:12
So let's go ahead and get down the givens.
00:15
M1, 1, 1 ,200, and then v1 equals.
00:25
Just get this down.
00:36
So let's see, 50, 4 ,400, 35, 50, 4 ,400, 35.
00:45
Oh, that was kilometers per hour.
01:14
1 ,56.
01:27
Okay, and they all stick together.
01:28
And i think they're all moving the same direction, right? so same direction.
01:37
If it's up from behind, it's also the same direction.
01:40
So this is going to be, you can use momentum conservation.
01:44
They all stick together.
01:45
So we can't use kinetic energy conservation, but that's okay.
01:50
We don't need it.
01:51
So we can say the initial momentum is equal to the final momentum.
01:54
So the initial momentum is m1 v1 plus m2 v2 plus m3 v3.
01:59
And the final momentum is m1 plus m2 plus m3 times their final velocity...