In mechanics we use four
fundamental quantities called dimensions. These are length, mass, time and
force. The units used to measure these quantities cannot all be chosen
independently because they must be consistent with Newton' second
law. Because of this, the units used to measure these quantities
cannot be all selected arbitrarily. The equality F = ma is maintained only if
three of the four basic units, called base units, are arbitrarily defined and
the fourth is then derived from the equation. Although there are many different
systems of units, only SI system of units will be used in this blog.
