# Unit conversion - stress-wave propagation speed

1. Aug 16, 2015

### omidd

Dear Friends,

The stress-wave propagation speed is calculated using : sqrt (elastic modulus/density)
The unit of elastic modulus is GPa, and that of density is gram/cm^dim

Can anyone please tell me how I can convert the resulting value to m/s (meter/second)?

Regards

2. Aug 16, 2015

### SteamKing

Staff Emeritus
I'm not sure what cm^dim is.

Any density given in g / cc can also be converted to kg / m3

Pascals are derived units. Write pascals in terms of basic units and see what's left after dividing by density.

3. Sep 18, 2015

### caz

Using these units (GPa and gm/cc) the velocity is in km/s so multiply by 1000

4. Sep 20, 2015

### Staff: Mentor

Instead of learning 20 different cases, it is easier to learn how to convert units in general:

GPa = 109 Pa
kg = 1000 g
m = 100 cm, which implies m3 = 1003 cm3
All those are universal SI prefixes.

Pa = N/m2

If you plug in your units, convert them and simplify, you'll naturally get the correct result.