Document 17550954

There are two types of measurement
 Quantitative measurements have a definite form
and are usually expressed as numbers with units.
▪ E.g. 3.05 grams, 12 liters, 4.5 grams/ml
 Qualitative measurements are descriptive and
have no numbers involved.
▪ E.g. It gave off a “reddish gas”, It had small bumps
Measurements can be either direct or
 Direct measurement can be taken straight from
an object.
▪ E.g. The length of an object in meters
 Derived measurements must have a
mathematical expression performed using several
direct measurements
▪ E.g. The volume of an object is length x width x height
Density is a very important derived
 Density = Mass
Density is an example of an intensive property
because it does not depend on how much of the
object you have on hand.
How do you know if your measurement are
true or not?
 Accurate measurements are measurements that
are very close to the true value of a measurement.
 Precise measurements are measurements that
are consistent, but not necessarily close to the
true value.
 The goal is to have measurements that are both
accurate and precise.
Think of a dart board.
The reliability of a measurement is expressed
by the number of significant figures that are