I am not sure if I understand the premises under which conservation of momentum can be considered. First of all, I am aware that momentum is conserved if there are no external forces acting on a system. So, if you are looking at two objects colliding, their momentums will always be conserved if there aren't any forces acting on the system itself.(adsbygoogle = window.adsbygoogle || []).push({});

This brings into question of actually solving for conservation of momentum. Is it always conserved during a collision? What kind of external forces can act during a collision? Is the momentum conserved if you bounce a ball on Earth?

Another thing I am confused about is the vector relationship to conservation of momentum. Say that before a collision, the object's momentum is conserved since the ground is frictionless. But after the collision, the object's velocity switches direction, yet the magnitude stays the same. In this case, is momentum still conserved? The way I had interpreted is to observep= mvand if the direction ofvchanges, then the final vectorpis changed. So does momentum change during the collision? If so, does it mean that it's not conserved?

Sorry for making this topic a little longer than I had hoped for.

Thank you in advance for any help

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# Conservation of Momentum: A Simple Question

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