_WCLN - Physics - 2D Momentum

Solving 2D Momentum problems using both the "trig method" and the "component method." This example uses a pool ball collision.
#momentum #impulse #physics #explosion #2d #pool

0:00at this point you soft lots of momentum problems that are very familiar with the
0:05conservation of momentum you started your momentum problems with Peavy for
0:12equals P after and your next step is recognizing the moving objects before
0:21and after the collision or explosion in this example we can see that object one
0:30is moving before object to is not moving and then after we have object one moving
0:41and object to moving represented as such we would then replace the momentum is
0:49with the corresponding embassies and we're ready to attack the problem we can
0:56rearrange your equation for the unknown plugin numbers then calculate in one
1:02dimension everything is moving along one line so the vector aspect of momentum is
1:09represented by simply deciding which direction we consider positive and
1:14ensure your velocities are represented accordingly
1:18objects moving in the positive direction get a positive velocity and those moving
1:23in the opposite direction
1:25get in negative velocity Mason simple
1:31will now progress into being able to do
1:34two-dimensional momentum problems will start the exact same way
1:39same underlying concept the conservation of momentum for Peavy for equals P after
1:46and then we identify the moving objects before and after a collision or
1:53explosion in a 2d problem that we have to do more than just plugging in envy
2:00and watching are positives and negatives we have to take into account the various
2:05directions of these momentum seems to do this we have two main methods we can
2:13call method one the trig method and method to that component method you'll
2:21need to understand both methods for this course as they are both powerful in
2:25their own ways let's lay out the main ideas behind each of these methods
2:34first we'll look at the trig method let's consider a collision between two
2:39objects coming in at different angles two-dimensional to collide and stick
2:46together and they move off out of the last tv3 both stuck together again we
2:52start with the conservation of momentum before equals P after and the same as a
2:59wonde problem let's consider all the items that are moving before and after
3:05this collision object one is moving before the collision so it has momentum
3:10so does object to and then the collision they moved together so let's call that P
3:19three treating them as one object this time though rather than moving forward
3:25by plugging in MVC and laying out an equation will represent this
3:29relationship as a vector diagram remember doing all the vector editions
3:35early in this course
3:36well here's where that pays off so before the collision we have object one
3:43coming in at an angle of 30 degrees so much so that the actor like this and
3:48we'll know the angle the second object is coming in at 10 degrees so we'll do a
3:54proper vector addition just like what is described in our equation on the left
3:59side we have p1 + p2 so we do have a tradition tale to head tail to head will
4:09note the angle key to here as well so we represented the left side of equation on
4:17the right side we simply have P three year since receiving that p1 + p2 equals
4:24P three we know that P three must start at the same starting point and end at
4:31the very same ending point and there we go our conservation of momentum is now
4:38shown as a vector addition at this point you can use a combination of cosine law
4:45and sign law
4:46to aim for your final answers often use the cosine law to determine the
4:52magnitude of the momentum and the sunlight to determine the angle
4:58let's jump into an explosion example again using the trig method in this case
5:05is still object explodes into three pieces all moving off in various
5:10directions again we start with the conservation of momentum before equals P
5:16after and same as before
5:19let's consider all the items that are moving before and after the explosion
5:24since nothing is moving before the explosion in this case will just put a
5:29zero here but after the explosion we have three moving objects so we can
5:35label them as p1 p2 mp3 the left side of this momentum equation is just zero so
5:44what we're really saying here is that the vectors on the right side of the
5:49equation have to all add up to be 0 that is they'll start and end at the exact
5:54same point so when we draw our vector addition we know that p1 + p2 + P three
6:02will bring us all the way around and back to the starting point so let's do
6:07it