# Homework Help: What mechanical paramater has a unit corresponding to expression

1. Nov 16, 2009

### helpme1

1. The problem statement, all variables and given/known data
What mechanical parameter has a unit corresponding to expression N2 sec3/kgm ?

2. Relevant equations
a.impulse b.time c.velocity d.energy e.force

3. The attempt at a solution

2. Nov 16, 2009

### srmeier

do you know what a newton is in SI units?

3. Nov 16, 2009

### helpme1

Force.

4. Nov 16, 2009

### srmeier

no, a newton is the unit of force but a newton can be broken down into simpler units of measure. this is the equivalency:

$$[N]=[\frac{Kgm}{s^2}]$$ -(these are the units for F=ma)

This should make sense to you, F=ma. "m" is measured in Kg, "a" is measured in m/s^2. when you multiply the two you get a unit of Newton

5. Nov 16, 2009

### helpme1

thanks for your response. but then the answer of question is Force ? right.

6. Nov 16, 2009

### srmeier

no, plug the SI expression for a Newton into the original expression, what units are left?

7. Nov 16, 2009

### helpme1

impulse ?

8. Nov 16, 2009

### srmeier

you got it! ^^

9. Nov 16, 2009

### helpme1

ah thanks! :) you are helpful. i did it by thinking. at last i did a physics test my own (of course with your help)