### Video Transcript

What must a vector quantity have
that a scalar quantity must also have? (A) A magnitude, (B) a
direction.

This question is asking us to
identify a property that both vector and scalar quantities have. Let’s recall that a scalar quantity
is a quantity that can be fully defined by only a magnitude. One example of a scalar quantity is
speed. For example, we could say that this
person has a speed with a magnitude of three meters per second. We don’t need to give any more
information here, because the speed is fully described by this magnitude. That is, the speed is simply three
meters per second.

Let’s now recall that a vector
quantity must be described in terms of both a magnitude and a direction. An example of a vector quantity is
velocity. We can see that this person is
moving to the east. To fully describe their velocity,
we need to give both the magnitude and direction of this velocity. The magnitude is three meters per
second, and the direction is east. The velocity is therefore three
meters per second to the east. If either the magnitude or
direction information was missing, the velocity would not be fully defined.

So we have seen that a scalar
quantity has a magnitude and a vector quantity has both a magnitude and a
direction. So, as to which property is common
to both scalars and vectors, the answer is magnitude. The correct answer is therefore
option (A). Scalar quantities and vector
quantities must both have a magnitude.