00:01
All right, chapter four, problem number five, we have two dogs pulling on two ropes.
00:04
Dog a pulling at 270 newtons and dog b pulling at 300 newtons at an angle of 60 degrees to each other, and they want to know the magnitude and direction of the resultant force.
00:15
So we're adding these forces together.
00:17
I've put a going straight in the x direction.
00:20
That makes it easy to find the components of a.
00:22
So our vector a in unit vector notation is going to be 270 newtons in the i direction, it's positive.
00:30
It's positive there.
00:32
And we're going to have zero newtons in the j.
00:34
It doesn't even have a y component.
00:36
For vector b, we can go ahead and find those components.
00:40
This red one here is going to be our horizontal component.
00:43
And this blue one i draw in here is going to be our vertical component.
00:47
And the horizontal component we can see is cosine.
00:51
So we are going to do the hypotenuse of that triangle times the cosine of 60.
00:57
That's going to be b in the x direction.
00:58
So b sub x is going to be 300 times the cosine of 60 degrees...