00:02
Hello, this is instructor nicole going to solve your problem here about the amount of work done so what do we know about work? well work is equal to force times displacement okay, so let's set up your situation here.
00:19
We have a package i'm just going to represent it by this point pushed across the floor of 60 feet.
00:28
Okay.
00:28
So here's our displacement.
00:30
That's one important thing to know of 60 feet by exerting a force of 42 pounds downward at an angle of 20 degrees from horizontal so downward angle of 20 degrees from the horizontal let's take this force vector out by itself because what we need to know here is work is only done in the same direction as the displacement so we're gonna have to break this force vector down into its component parts okay, because we can only count the part that is in the same direction as the displacement which i've drawn from left to right it's not specified in your question.
01:31
So that doesn't matter okay, so let's break this force vector down and we do know the amount this force vector is 42 pounds of force and we know that it is at an angle of 20 degrees from the horizontal okay so this is going to be the horizontal component of our vector right here.
01:58
That's the part that we want that's in the direction of our displacement the horizontal component would be here which we're not interested in for purposes of this problem.
02:14
So to find the horizontal force component f of x we do the force total force which is our 42 pounds in this case times the cosine of the angle which is 20 degrees in this case if it would be wanted the y component we would use sine so a catch here though is we have this force and 42 pounds we're gonna need to change that to newtons so let me do that up here okay, our conversion factor for that is that? 1 newton equals about 4 .4 pounds okay you know, i said that backwards and that's really important to correct that...