00:01
Okay, you have a block of mass m on a rough, inclined surface.
00:08
So let's draw that.
00:10
There's our inclined surface.
00:13
Here's our block.
00:17
And let's draw the angle here.
00:21
So something like that, right? call that incline angle theta.
00:27
And that's what we're trying to solve for here.
00:34
So we want to show that you can obtain the coefficient of static friction just by measuring the critical angle.
00:41
So let's see if we can show this.
00:46
We're going to use forces, right? we want to use forces.
00:51
So let's draw the forces, and we'll shift our coordinates.
00:55
You always do that with inclined blocks.
01:01
So downward we have the weight, so mg.
01:07
Normal to the slope, we have the normal force.
01:10
And then up the slope is the frictional force.
01:16
Okay.
01:19
Those are the only forces, right? and basically you raise the angle more and more until if you raise it any more, the block would start to slide...