00:01
All right, there is a drawing in the book, and i'm going to try to draw it.
00:14
So we've got a mass here, and then it goes up, oops, connects here, up to a pulley, and down.
00:30
Okay, there's a length x here, and then there's t here.
00:45
Okay, so what is the question? the mass is 2 .2 kilograms.
01:09
The tension in the rope is 10 newtons.
01:17
And there is some acceleration.
01:24
And the pulley is 10 centimeters above the block.
01:30
What's this mean again? and the pulley is 10 centimeters above the block.
01:38
Was that shown in the drawing? because i'm not sure that that's clear enough, at least not for me.
01:45
The pulley is 10 centimeters above the block.
02:00
All righty.
02:00
Well, i guess it's just telling us that the distance here, 0 .10 meters.
02:31
Coefficient of friction is 0 .4.
02:39
Okay.
02:44
What's the acceleration when x is 0 .4? okay.
03:05
So let's take the block here.
03:17
It's got a tension force here, and then it's got an angle, which i'm going to take call phi.
03:34
Now, the tangent of phi is going to be the opposite, which is d over the adjacent, which is x.
03:53
Would be the inverse tangent of d over x okay now the sum of the forces i'm going to have to sum the forces in the x direction and the y direction um let's do y first in the y direction in the y direction i'm going to have t -sign phi, t -sign phi, and then there's also a force acting downward, and there's a normal force.
05:03
So t -sign -fi plus the normal force minus m -g, 0.
05:22
So the normal force is going to be m g minus t sine phi.
05:34
Now, in the x direction, we've got t cosine phi minus the frictional force.
05:54
The frictional force would be the normal force times mu.
06:00
Okay, and then that's going to equal the mass times the acceleration.
06:21
Okay, let's put in what we know.
06:26
T is 10, d is 0 .1, m is 2 .2.
06:49
10 .1, 2 .2.
06:52
10, 0 .2.
06:54
Mue is 0 .4, x is also 0 .4.
07:08
Okay.
07:12
Phi is going to be the inverse tangent of d over x.
07:24
I think i'm going to have to call this x1, and then i'm going to have to put in x1 here so that it's useful.
07:31
Okay, so that's 14 degrees.
07:38
Then here, what are we trying to figure out? we're trying to figure out the acceleration.
07:43
So i need t cosine phi minus mu, mg minus t sine phi.
08:28
Okay.
08:28
And then i have to divide by the mass...