# Ns and N/s

1. Aug 29, 2006

### danago

Hey. Im having a little trouble differentiating between newtons per second ($N s^{-1}$) and newton seconds (N s). I know that N/s is a measurement of a certain number of newtons over a period of 1 second, but could someone please explain what a newton second is?

Thanks,
Dan.

2. Aug 29, 2006

### e(ho0n3

Ns is a unit used to quantify momentum.

3. Aug 29, 2006

### danago

momentum? I thought momentum was usually measured in kg m/s? ISnt Ns used to measure impulse?

4. Aug 29, 2006

### e(ho0n3

Well, N = kg m / s^2 and Ns ends up being kg m / s.

5. Aug 29, 2006

### Staff: Mentor

So what are units of N/s used for? N*m/s would be power, so N/s is power per distance? Where did you see these units pop up, danago?

6. Aug 30, 2006

### danago

For impulse. Since $I=F \Delta t$, therefore, its unit would be Ns wouldnt it?

7. Aug 30, 2006

### Hootenanny

Staff Emeritus
Yes, Newton-seconds is the unit of impulse. However, I can see where the confusion arose with respect to momentum, since the change in momentum is equal to the impulse.