Conservation of momentum & inelastic collisions

AI Thread Summary
The discussion centers on whether the principle of conservation of momentum is violated during a ball's collision with the ground in an experiment. It is established that the conservation law applies to closed systems, and the ball-Earth system is considered a closed system during the collision. Participants clarify that the gravitational force exerted by the Earth on the ball is not an external force within this system. The conversation emphasizes that while momentum is conserved in the Earth-ball interaction, external forces, like those from the Sun, are negligible for this scenario. Overall, the conclusion is that momentum conservation holds true in this context.
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Homework Statement


This question is related to an in-class experiment. The lab involves bouncing a ball and using a motion sensor which creates a graph representing the motion.
The question is: Is the principle of conservation of momentum violated in this collision (the ball colliding with the ground)?


Homework Equations


m1v1i + m2v2i = m1v1i + m2v2i


The Attempt at a Solution


I don't think the collision violates the conservation of linear momentum law because the law applies to closed systems, and this system (when the ball collides with the earth) is not closed.
However I'm not sure if my theory on this is correct ...

Thanks in advance for your help :)
 
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What does your system consist of? Is it just the ball? What have you learned about momentum conservation, namely when is momentum not conserved?
 
The experiment only involves bouncing a ball on the ground (and detecting motion). Therefore, I am not sure if the system involves both the ball and the ground, or just the ball.
Regarding momentum, I know that momentum is always conserved in a closed system, but not a system which is affected by external forces.

thanks for helping :)
 
In a collision there are always at least two parties that participate, an object cannot collide with itself. One party is the ball so it is reasonable to assume that the Earth (or floor which is attached to the Earth) is the other party. Is the Earth-ball a closed system? Are there external forces that affect it?
 
Okay, so if the system is the earth-ball (and the collision between the two)... I'm not sure if the gravitational force from the Earth on the ball is included in the system, or is counted as an external force?
 
It is not external to the Earth-ball system. The force that the Earth exerts on the ball is equal and opposite to the force that the ball exerts on the Earth. The Sun's force on the ball and Earth would be an external force, but we pretend that it is negligible.
 
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