Conservation of momentum in a system, direction changes?

In summary, the conservation of momentum in a system is well-known. However, there may be confusion regarding the movement of a ball after colliding with a wall at a 45 degree angle. It is possible for the ball to move in a different direction than its initial trajectory, depending on factors such as friction and spin. If the wall is able to be rotated, the ball can be directed in any desired direction.
  • #1
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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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  • #2
I don't fully understand your question. However the incident direction and the reflected direction are in the same plane.
 
  • #3
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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1. What is the conservation of momentum in a system?

The conservation of momentum in a system refers to the principle that the total momentum of a closed system (a system with no external forces acting on it) remains constant. This means that the total momentum before an event or interaction is equal to the total momentum after the event or interaction.

2. How does conservation of momentum apply to direction changes?

Conservation of momentum applies to direction changes in a system because the total momentum of the system must remain constant. This means that if one object in the system changes direction, another object must change direction in the opposite direction to maintain the total momentum of the system.

3. What is the relationship between mass and momentum in conservation of momentum?

The relationship between mass and momentum in conservation of momentum is that the momentum of an object is directly proportional to its mass. This means that a heavier object will have a greater momentum than a lighter object moving at the same velocity. In conservation of momentum, the total momentum of the system is determined by the mass and velocity of all objects in the system.

4. How does conservation of momentum affect collisions?

Conservation of momentum plays a crucial role in collisions because it dictates that the total momentum before and after a collision must be the same. This means that the objects involved in the collision will transfer momentum to each other, resulting in changes in their velocities and directions.

5. What are some real-life applications of conservation of momentum in direction changes?

Conservation of momentum in direction changes is observed in various real-life scenarios, such as in sports like billiards or ice hockey, where objects collide and change direction. It is also used in rocket propulsion, where the momentum of the expelled gases causes the rocket to move in the opposite direction. In addition, the conservation of momentum is essential in understanding and predicting the motion of objects in space, such as planets and satellites.

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