00:01
Hello, here we have to solve the assignment.
00:03
So here there is a 6 kilogram crate on a frictionless incline, and we are pushing it with a force of f, that is 6, sorry, there is 170 newton's.
00:25
Mass of the crate is 6 kilograms, and angle is 55 degree to horizontal.
00:31
So let's briefly indicate mg.
00:35
So the gravity is exerting downwards, and n is perpendicular to the incline.
00:41
And for the simplicity, let's introduce y and x x.
00:45
And here, let's also show the angle alpha, which is formed by the coordinate axis.
00:53
So this angle alpha is this guy.
00:57
So therefore, the displacement will be upwards, and that's parallel to the x -axis.
01:03
So first, let's answer the first problem.
01:06
And here we have to calculate work done by the crate worker.
01:10
We have to calculate work done by the force f.
01:14
That equals to f times the displacement.
01:17
And here the displacement is along the applied force.
01:25
So the crate moves by l, which is 3 meters.
01:31
So therefore, the work done by the force f equals to the force itself, which is 170 newtons times 3 meters.
01:52
That is 510 joules.
01:59
So that's answered to the first question.
02:02
Now let's calculate work done by the gravity.
02:05
That equals to f to mg vector...