Length, mass, and time are the three fundamental dimensions on which the
measurement of all physical quantities is dependent.
DEFINE the three fundamental dimensions: length,
mass, and time.
LIST standard units of the fundamental dimensions for
each of the following systems:
International System of Units (SI)
DIFFERENTIATE between fundamental and derived
Physics is a science based upon exact measurement of physical quantities that are dependent upon
three fundamental dimensions. The three fundamental or primary dimensions are mass, length, and
time. These three fundamental units must be understood in order to lay the foundation for the
many concepts and principles presented in this material.
Mass is the amount of material present in an object. This measurement describes "how
much" material makes up an object. Often, mass and weight are confused as being the
same because the units used to describe them are similar. Weight (a derived unit, not
a fundamental unit) is a measurement that describes the force of gravity on the "mass"
of an object.
Length is the distance between two points. The concept of length is needed to locate
the position of a point in space and thereby describe the size of a physical object or
system. When measuring a length of pipe, the ends of the pipe are the two points and
the distance between the two points is the length. A typical unit used to describe
length is the "foot."