2D Conservation of Momentum Example using Air Hockey Discs (13:27)
A 28.8 g yellow air hockey disc elastically strikes a 26.9 g stationary red air hockey disc. If the velocity of the yellow disc before the collision is 33.6 cm/s in the x direction & after the collision it is 10.7 cm/s at an angle 63.4° S of E, what is the velocity of the red disc after the collision?
This is an AP Physics 1 topic.

Honestly, while this is an AP Physics 1 topic, I have yet to see a conservation of momentum problem on the AP Physics 1 exam which is in more than one dimension. This is certainly covered on the AP Physics C: Mechanics Exam, however, I don't think it actually is on the AP Physics 1 Exam. Does anybody have information which contradicts this statement?

Content Times:
0:12 The problem
1:49 Breaking the initial velocity of disc 1 into its components
3:06 Conservation of momentum in the x-direction
5:24 Conservation of momentum in the y-direction
6:26 Solving for the final velocity of disc 2 using its components
8:40 Was this an elastic collision?
12:39 Movie Character Day!
Here is a video students can use to make their own measurements.

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​If you were curious where the known values came from in the video: Here are my calculations.

Picture Credits: "Nombre de los vientos". Licensed under Public domain via Wikimedia Commons