# Basic units question

1. Feb 15, 2012

### JamesBX

Ok for the life of me i cant remember how you get from say 15 miles per hour (15m/h) to 15mh-1?

2. Feb 15, 2012

### CompuChip

Do you mean: 15 m/h to 15 m h-1?

There is no conversion there, it's just a different way to write the same thing. Dividing by the power of a quantity is the same as multiplying by the negative power, so
mi / h = mi h-1 (because you can read h as h1) and for example ft / s2 (as an acceleration) would be ft s-2.

3. Feb 15, 2012

### Integral

Staff Emeritus
really no where to go.

$$\frac 1 x = x^{-1}$$