Video Transcript
The components of the vector ๐ฎ are
negative one, negative two. As the terminal point of the vector
is negative one units right or one unit left and negative two units up or two units
down from the initial point. What are the components of the
vector ๐ฏ?
So this question begins by
explaining to us how to find the components of the vector ๐ฎ in the diagram. The terminal point is where the
vector ends, and the initial point is where the vector begins. And we can use the arrow on the
vector to determine its direction.
The arrow on the vector ๐ฎ is
pointing downwards to the left. So the initial point is the point
labeled in orange, and the terminal point is the point labeled in pink. We see that, to move from the
initial point to the terminal point, we have to move one unit to the left and then
two units downwards. We can also think of this as moving
negative one units right and negative two units up. This is because the convention when
writing the components of a vector is to list the number of units right first and
then the number of units up. So movements to the left and
movements down are expressed using negative values.
Letโs now consider this vector
๐ฏ. We can see that the arrow on this
vector is again pointing downwards to the left. So the initial point is the point
on the top right, and the terminal point is the point on the bottom left. To move from the initial point to
the terminal point, we move one, two units left first of all. And we then have to move one, two,
three, four units down.
But remember, when we describe this
as a vector, we need to describe the motion right and up. So two units left can be written as
negative two units right, and four units down can be written as negative four units
up. Using this convention then, the
components of the vector ๐ฏ will be negative two, negative four.
There is actually a special
relationship between the vectors ๐ฎ and ๐ฏ in this question. If I draw the vector ๐ฎ right next
to the vector ๐ฏ, we can see that these two vectors are parallel. Theyโre traveling in the same
direction. But the vector ๐ฏ is twice the
vector ๐ฎ. Two lots of the vector ๐ฎ make up
the vector ๐ฏ. So we could also answer this
question by saying that the vector ๐ฏ is equal to twice the vector ๐ฎ. Thatโs two multiplied by the vector
negative one, negative two.
To multiply a vector by a scalar โ
thatโs just a number, in this case two โ we multiply each of the components by that
scalar. So the first component will be two
multiplied by negative one, and the second component will be two multiplied by
negative two. That gives the vector with
components negative two, negative four, which is what weโve already found the vector
๐ฏ to be using the diagram. So by considering two approaches,
we have our answer to the problem. The vector ๐ฏ in component form is
negative two, negative four.
