The units of force are the dyne (d) and Newton (N). The units of a Newton are kg-m/s2 while those for a dyne are g-cm/s2. A Newton then, is the force required to impart an acceleration of one meter per second per second to a body of one kilogram mass. In similar terms, a dyne is the force required to impart an acceleration of one centimeter per second per second to a body whose mass is one gram (Davis and Reynolds, 1996). Thus, the units of stress are simply N/m2 or d/cm2, or, as it turns out several other more complicated but equivalent terms.
For example, shown in Table 1 are ten common units that geologists use to describe the units of stress and the conversion factors that can be used to switch from one to another.
|
Units
|
MPa Equivalent
|
| Megapascal (MPa) |
1.0
|
| Gigapascal (GPa) |
0.001
|
| Pascal (Pa) |
1,000,000.0
|
| N/m2 |
1,000,000.0
|
| kg/cm2 |
10.197
|
| d/cm2 |
100,000,000.0
|
| Bar (b) |
10.0
|
| kilobar (kb) |
0.01
|
| Pounds per square inch (psi) |
145.03
|
| Atmosphere (atm) |
9.869
|