# General question regarding Momentum

1. Oct 8, 2005

### ms. confused

General question regarding "Momentum"

Hi! Is it possible to have negative momentum?

I would think that as long as it's before a collision, this is not possible because an object would be moving forward, therefore having a positive velocity. After a collision (given that it is inelastic), however, the object most likely will move in the opposite direction, in which case the velocity is considered to be negative, which in turn makes the momentum negative.

Does this sound logical, or am I completely missing the point?

2. Oct 8, 2005

### arildno

Of course; it is possible for objects to travel either left or right, don't you think?

3. Oct 8, 2005

### ms. confused

Yes, but it all depends on whether it is before or after a collision does it not?

4. Oct 8, 2005

### ms. confused

Does collision have anything to do with it???

5. Oct 8, 2005

### mezarashi

Momentum is not a scalar. Meaning that it isn't just a number like the amount of money you have, or energy and power.

Momentum is a vector, meaning it has direction. Automatically things that are vectors CAN be negative. Take for example velocity or speed. If walking forward is positive then walking backwards is negative. If pushing forward means you've got positive momentum, then striding backwards would mean you have negative momentum. =)

6. Oct 8, 2005

### arildno

No, not really.
Every object has (a possibly zero) momentum, whether or not it collides with anything.