# Spring problem in British units

1. Apr 8, 2009

### joemama69

1. The problem statement, all variables and given/known data

ok this might be a stupid question but im working on a problem with springs and velocity and whatnot. anyways the units are american, 5lb, k=2lb/in, the diagram is dimensioned in inches. do i have to convert all them to N,kg,and meters.

2. Relevant equations

3. The attempt at a solution

2. Apr 8, 2009

### Cyosis

Re: springs

I'm not American nor have I ever used the imperial system for units, however seeing as the topic is called springs, I assume you're wondering if you can plug the values in Hooke's law without worrying about units? You can but you have to be careful, for example: $$F=-k x=- \frac{2 lb}{in} 5 in=10 lb$$. So the unit of force is now pound-force instead of Newtons. Just don't mix SI units with imperial units in the same equation.