Conservation of momentum in a system, direction changes?

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SUMMARY

The discussion centers on the conservation of momentum during a collision between a ball and a wall. It is established that while momentum is conserved, the direction of the ball post-collision can vary based on the angle of incidence and the wall's orientation. If the wall is rotated, it is possible for the ball to move in any desired direction, including the +x direction, even without friction. The presence of friction and spin can further influence the ball's trajectory after the collision.

PREREQUISITES
  • Understanding of classical mechanics principles, particularly momentum conservation.
  • Familiarity with collision dynamics and angles of incidence.
  • Knowledge of friction and its effects on motion.
  • Basic grasp of coordinate systems, specifically x-y axes.
NEXT STEPS
  • Study the principles of momentum conservation in elastic and inelastic collisions.
  • Explore the effects of friction on collision outcomes in classical mechanics.
  • Learn about angular momentum and its role in collision dynamics.
  • Investigate how varying angles of incidence affect the trajectory of projectiles.
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Students of physics, educators teaching mechanics, and anyone interested in understanding the dynamics of collisions and momentum conservation.

x86
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We all know that momentum is conserved in a system. But I am confused of one thing.

Suppose we have a system containing a wall with very large mass and a ball and use a classical x-y coordinate axis.

If I swing the ball at an angle of 45 degrees from the horizontal, upwards to the huge wall (which is at rest),

is it possible for the ball to move in a different direction that isn't collinear to its current direction after collision?

Say, after coliding with the wall, can the ball move in the +x direction?

Or will it always be bound to move on the on the 45 degree horizontal line?

I suspect that if we change the angle of colision, i.e. we rotate the wall, then we can make the ball move in any direction we want.

Is this true?
 
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I don't fully understand your question. However the incident direction and the reflected direction are in the same plane.
 
x86 said:
Say, after coliding with the wall, can the ball move in the +x direction?
A real ball with friction and spin can do that.
No matter how exactly the ball will move afterwards, the wall takes the corresponding momentum change in the opposite direction (this can include a vertical component if you consider friction).

If you can rotate the wall, then you can get every direction even without friction, sure.
 
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