Unit conversion chart

Queries regarding MKS to CGS system for the following formulas :

  1. Force $=$ Newton (MKS), Dynes (CGS)

$$\mathrm {1\ N = 10^5 \ dynes}$$

  1. Work $=$ Joule (MKS), Ergs (CGS)

$$\mathrm{1\ J = 10^7 ergs}$$

How the above unit conversion formulas are derived?

  • $\begingroup$ What have you already considered in trying to work out the answer for yourself? Where did you get stuck? $\endgroup$
    – The Photon
    Feb 20, 2022 at 6:15

1 Answer 1


They are defined but only in so much that there is an SI defined link between $1\,\rm kg \leftrightarrow 1000\,g$ and $1\, \rm m \leftrightarrow 100\,cm$.

For example, $1\,\rm J = 1\,kg\,m\,s^{-2} = 1\,(1000\,\rm g)\cdot(100\,cm)\cdot(1\,s^{-2}) = 10^5\,g\,cm\,s^{-2} =10^5\,dyne$.

However these two units are no longer a recognised part of the SI family of units although they are still used in various branches of science and engineering, eg Are ergs commonly used in astrophysics? If so, is there a specific reason for it?.


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