00:01
Okay, we're calculating the magnitude of the normal force acting on this 25 .2 kilogram block.
00:07
So the block is on a level surface.
00:12
First off, okay, general strategy for these problems.
00:22
Draw a picture, define a coordinate system, and draw the forces.
00:29
You can draw the forces before you define the coordinate system too.
00:34
That works.
00:36
And then apply newton's second law.
00:38
Some of the forces, in this case we're going to do it in the wide.
00:41
Direction equals ma decide if it's accelerating or not so this one is not accelerating it's just sitting there some of the forces in the y equals zero so the normal force minus m g equals zero so the normal force equals m g again this is a 25 .2 kilogram block so our normal forces 246 .96 newtons block is on a horizontal or not a horizontal surface.
01:19
It's tilted up at this angle.
01:26
That's kind of a crooked horizontal.
01:28
There we go.
01:31
It's tilted up at this angle.
01:32
Theta, which is 25 .8 degrees.
01:39
If you have a block on a tilted surface, you want to almost always change your coordinates so that x is parallel and y is perpendicular to the slope.
01:52
Okay, next let's draw the forces.
01:55
We'll draw them separately on this block.
01:57
So this is a free body diagram.
02:00
This is separate from the picture.
02:05
So gravity's pulling down...