The S.I. units are preferred. There are other systems which remain of importance in various
parts of the world and in particular fields of activity. The M.K.S. absolute units, so far as mechanics
is concerned correspond with S.I. units and it seems possible that MKS units may continue in use
for sometime along with S.I. units. Detailed conversion tables from one system to another can be
prepared. To change over from MKS system to S.I., just remember the following points.
1. The unit of force in M. K. S. system is kilogram force (kg f) or simply (kg).
2. The unit of force in S.I. units is newton (N)
3. One kilogram-force= g newtons
4. The value of g =9·81 m s-2
Therefore one kg f=9·81 N ________________________ (1)
For example, the unit of pressure in M.K.S. system is kg f/cm2 and convertion of 150 kg f/cm2 to
S.I. units is required.
Now,150 kg f/cm2 = 150 x 9.81 N / ( 10 mm )2
＝14.715 N/mm2=15 N/mm2
Thus,we may conclude that the current metric unit of pressure, viz. one kg f/cm2 is equal to 1/10
i.e. One kg f/cm2 = 1/10 N/mm2 ________________________ (2)