1. SIGNIFICANT FIGURES Physics is called a quantitative science
because it describes nature using quantities which are
measurable, and seeks to discover mathematical laws relating
these quantities. You may be already familiar with some of these
quantities: length, time, mass, force, etc. To measure such
quantities, we use measuring instruments in a prescribed way in
order to assign a number (value) to that quantity. For example,
to measure a length we use a measuring instrument (a marked
meter stick) in a specially prescribed manner (laying the stick
off on the object to be measured) to determine the numerical
value we call the "length." Other measurements may require more
complicated instruments, or more complex techniques, but the
principle is the same. The meter stick example also illustrates
the uncertainties common to all measurements. The smallest
division marks on the stick represent millimeters. These are
quite small, but with a little practice, most persons can
estimate fractions of millimeter. Estim