# Understanding momentum concept

1. Oct 28, 2012

### Maisara-WD

Hello

Please, if you UNDERSTAND WHAT IS MOMENTUM, tell me.

I want to know, why do I need momentum, why was this concept introduced. If I were an ancient scientist, what's the problem that faced me in absence of such concept, that lead me to devising it, and at which basis did I choose my independent variables, mass and velocity.

2. Oct 28, 2012

### Maisara-WD

I've forgot to say:

Mu readings have lead me that the concept was introduced in order to account for the uniform motion (assume it's space with no resistances), that a body makes although the physical interaction causing it to move disappeared.

I still don't get it, I think the answer is simply because that body has a kinetic energy! and energy is conserved, there's no resistance, no consumption, let the body move because of its energy.. why momentum?? why to think that energy interpretation is not enough, and that I need another sufficiently explaining concept?

3. Oct 28, 2012

### Staff: Mentor

There are many cases where mechanical energy is not conserved, yet momentum is

Momentum is also a vector quantity, kinetic energy is not.

4. Oct 28, 2012

### Maisara-WD

Let's say it's conserved, WHY to introduce a new concept? is just because of the scalar nature of energy quantities?

5. Oct 28, 2012

### Staff: Mentor

Any time you can introduce a new quantity that is conserved it expands your power to understand the world. Take the simplest case: A ball collides with another at rest. Assuming kinetic energy is conserved doesn't allow you to predict what will happen. Adding momentum conservation does.

6. Oct 28, 2012

### Maisara-WD

That's acceptable :D

Thanks ALOT :)