# Relationship between momentum and acceleration, and force

1. Jun 19, 2009

### Self-Help

1. The problem statement, all variables and given/known data
I am trying to understand physics in terms of relationships rather than just equations, hoping this site would help me, thanks!

So... You can expect lots of questions from me lol.

Okay so right now it is momentum and acceleration. Trying to understand what could be a qualitative relationship between acceleration and momentum of an object

2. Relevant equations
p=mv

3. The attempt at a solution

I realize p$$\propto$$mv
therefore p$$\propto$$m * at

so since momentum is proportional to mass, acceleration and time, I am assuming when I have two momentum vectors - say, tail of vector p2 is attached to the head of vector p1-, acceleration vector of that object points in the same direction as the resultant vector of p1 and p2? By that order force is applied also in that direction?

Thanks!

2. Jun 19, 2009

### Nabeshin

Without a diagram it's a bit hard to follow you but I think what you're getting at it close. The acceleration vector points in the direction of p2-p1 (the difference, or change, in momentum).

Be careful though because v=at only for cases of constant acceleration.

I think you might find the relationship $$F=\frac{dp}{dt}$$ interesting. Basically, the force is equal to the change in momentum with respect to time. So, it makes sense that a force is in the same direction as the change in momentum.

3. Jun 19, 2009

### rl.bhat

If the mass is moving with uniform velocity, p α m only.
During the interaction of 2 momentum, you can consider the action and reaction forces.