# Homework Help: How is the direction (vector?) of momentum stored physically

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1. Dec 14, 2015

1. The problem statement, all variables and given/known data
I am not a student, but one poster was kind enough to answer my stupid question last week, and I was wondering if anyone would mind if I posted another stupid question.

When an object is moved in a specific direction, how is the direction of momentum stored or recorded. By this I do not mean how is the vector calculated, but how is the information stored (as a particle?). Also is any research being done into this if the answer is not known.

2. Relevant equations
None

3. The attempt at a solution

Absolutely none.

2. Dec 14, 2015

### SteamKing

Staff Emeritus
You're confusing a mathematical model with reality. We represent things like forces as vectors because we find it useful and convenient to make calculations with vectors, not because a 'force' carries around a magnitude and a direction with it all the time. These things like vectors are just numbers.

Things like momentum are also relative to the observer. For example, if you are riding in a elevator with an apple in your pocket, the apple is not moving, relative to your pocket; therefore it has zero momentum. To someone standing outside the elevator, it is clear that the person inside the elevator is moving, with respect to that external frame of reference, and that that person and anything he is carrying has momentum.

3. Dec 14, 2015

My stupidity is getting in the way again. What I am trying to say is much simpler really. Why do objects continue to move in any particular direction? Is there a particle that carries the direction?

4. Dec 14, 2015

### SteamKing

Staff Emeritus
No, the motion of a body is described by Newton's Laws of Motion.

https://en.wikipedia.org/wiki/Newton's_laws_of_motion

Specifically, the First Law of Motion states that a body moves at constant velocity unless it is acted on by an external force. The direction of motion of the body changes, depending on where this external force is applied to the body.

5. Dec 14, 2015

Thank you so much for your help. How do I upvote you?

6. Dec 14, 2015

### SteamKing

Staff Emeritus
Thank you for the compliment. I don't think PF votes likes and dislikes.