00:01
Hello and welcome.
00:03
We're looking at chapter 12, section 2, problem 32, where you're given lengths and directions and asked to find the resultant vector.
00:15
Remember that a vector can be defined by its magnitude multiplied by its direction.
00:21
Direction can also mean unit vector.
00:24
Notice that this here is the definition of a unit vector.
00:30
So in other words, magnitude is.
00:33
Is the length.
00:36
So if you multiply the length times the direction, you get your vector.
00:41
So let's move these over.
00:52
So if you're given length 7, direction negative j, the vector is just going to be the length times the direction, which is negative 7j.
01:07
So that's the length times the direction is the vector.
01:11
You're given the length.
01:12
You're given the direction.
01:14
This is a vector and you can check if you don't believe me.
01:19
And so you can just multiply them to find the vector.
01:22
So that's all this question is asking.
01:24
So for part a, this would be your answer.
01:28
For the next one, the length is root 2.
01:31
The direction is negative 3 fifths i minus 4 fifths j.
01:43
So for this one, as long as we multiply this root 2, length times direction is the vector.
01:49
It's one way to define the vector.
01:52
So as long as i multiply this by both components, by both terms, i have it.
01:58
So this would be negative root, negative 3 root 2 over 5.
02:04
Make sure i can't simplify any of that, which i can't.
02:07
Minus 4 root 2 over 5j.
02:12
So i can't simplify this either.
02:16
So that is the length times the direction that helps me define the vector.
02:21
So that's part b.
02:24
If the length is 1312th and my vector is a following, i have to multiply my length by my vector and by my direction.
02:50
And that's going to give me, that's going to define the vector.
02:53
So the length times the direction, this is a unit vector as well.
02:56
You can check it...