00:01
So we've got this mass here, which is a pencil box.
00:07
And we are connecting to a pen box up here.
00:11
Pencil box's mass is one kilogram.
00:13
And i chose this to be m2, even though it's listed first.
00:19
It doesn't really matter which when you make m1 and m2.
00:22
It's just the way that i drew it.
00:24
So the pencil box's mass is one kilogram.
00:27
The pen box's mass is three kilograms.
00:29
And the pencil box is on this 30 degree incline.
00:34
And both of these surfaces are frictionless.
00:38
So the first part of this problem, we need to figure out the tension force.
00:45
So for that, i'm going to first write out the sum of all the forces acting on each of these two boxes.
00:52
And we'll start with m1.
00:53
We're going to have m1 times a.
00:56
That is the net force.
00:58
That's going to be equal to the force that we are applying.
01:02
That's that 2 .3 newton force that is being applied to m1.
01:07
And then we're actually going to add to that the tension force because these are going to be in the same direction.
01:16
And that's all the forces acting on m1.
01:19
And then we've got m2 times its acceleration.
01:28
And that's going to be the force.
01:32
Is acting in the parallel direction to this slope.
01:36
So it's going to be the weight force, the parallel part of the weight force.
01:42
So m2g sign of theta, where theta is that 30 degrees, and then subtract the tension force in this case, because the tension force is back up.
01:55
So we don't care about the acceleration other than they should have the same acceleration.
02:00
So to find the tension force, we're going to have to substitute in for it.
02:08
So i'm just going to solve this first equation for acceleration.
02:13
So i do that by dividing both sides by m1.
02:16
I get acceleration is equal to the force plus the tension all over that m1.
02:25
And then i'm going to plug this into here.
02:28
So i'm just going to take that.
02:30
I'm going to plug it into this equation.
02:31
And then i'll have one equation with one unknown, the tension.
02:36
So m2 times force.
02:41
I'll just go m2 over m1 times force plus tension is equal to m2g sine theta minus tension.
02:52
And so i'm going to get all my tensions over on this side...