Unit conversion - stress-wave propagation speed

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Discussion Overview

The discussion revolves around the conversion of stress-wave propagation speed from units derived from elastic modulus (GPa) and density (grams per cubic centimeter) to meters per second (m/s). The scope includes unit conversion techniques and the relationships between different measurement units in the context of physics.

Discussion Character

  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant states the formula for stress-wave propagation speed as sqrt(elastic modulus/density) and seeks guidance on converting the resulting value to m/s.
  • Another participant expresses uncertainty about the term "cm^dim" and suggests converting density from grams per cubic centimeter to kilograms per cubic meter.
  • A different participant claims that using the given units (GPa and grams per cubic centimeter) results in a velocity in kilometers per second, recommending multiplication by 1000 to convert to m/s.
  • Another response reiterates the conversion of GPa to Pascals and provides a breakdown of unit conversions, emphasizing the importance of understanding the underlying relationships between units.

Areas of Agreement / Disagreement

Participants present multiple approaches to unit conversion, with no consensus on a single method. The discussion includes varying interpretations of the units involved and different suggestions for conversion techniques.

Contextual Notes

Some assumptions about unit definitions and conversions remain unaddressed, and there are unresolved steps in the mathematical reasoning presented by participants.

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

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