Video Transcript
Can some scalars have values that
are negative as well as values that are positive?
In this question, we are asked
whether some scalars can have values that are negative as well as values that are
positive. Let’s begin by defining what a
scalar is. A scalar is simply a quantity that
is fully defined by a magnitude. Examples of scalar quantities are
distance, temperature, and mass. Note that a scalar is different
from a vector quantity, because a vector quantity is defined by both magnitude and
direction. Sometimes, the direction of a
vector quantity can determine whether it has a positive or negative value. But when measuring a scalar, the
direction of measurement does not matter. For example, the temperature
measured by a thermometer will be the same if the thermometer is right side up or
upside down.
So can a scalar quantity still have
both positive and negative values? Well, yes. Let’s think about this example of
temperature. We know that it’s possible for
temperatures to have positive values. For example, the boiling point of
water is 100 degrees Celsius. This is a positive value. But temperature can also have
negative values. For example, the inside of a
household freezer is typically set to a temperature of minus 20 degrees Celsius. This is a negative value. So when measured in degrees
Celsius, temperature can have both positive and negative values. So the correct answer is yes,
scalars can have values that are negative as well as values that are positive.
However, we should be careful to
note that this is not necessarily true for all scalars. For example, it is impossible to
travel a negative distance. Distance is a scalar quantity that
can only have positive values. So whilst scalars can have values
that are negative as well values that are positive, not all scalars do.
