00:01
Okay, so for number one, we're looking for how a small force could exert a large torque or vice versa.
00:06
So we need to start talking about what is torque.
00:09
Torque is force times radius.
00:13
Now, it's not really radius.
00:14
It's actually called the lever arm.
00:16
Lever arm is the distance between the pivot and the force.
00:20
So if you had like, i don't know, a rod that was pivoting around something like this, and you had a force that was applied right here, then this would be r.
00:30
The radius of this circular motion or the distance between the force and the hivot.
00:39
Okay, so now there's one other component to torque and that is these must be perpendicular to each other.
00:44
So in this case, i've got r that's horizontal and the force that's vertical.
00:48
That's a good example of when a torque would be at its maximum.
00:52
Alright, so now to answer the question, how could you have a small force but a large torque? well, there's two components to the torque.
01:00
If you have a small force, you would need, i'm going to say would require a large radius or lever arm.
01:18
So you don't need a real big force if you've got a big distance from the pivot.
01:22
Okay, and then same thing for large force exerting a small torque.
01:26
Yeah, large force exerting a small torque.
01:29
You could have a large force would require a small radius or lever arm.
01:47
So just because there are two components to it, you can have a small torque with a small radius or a big torque with a big radius, etc.
01:55
The force is not the only factor that's involved.
02:00
Okay, second question is asking about rotational inertia.
02:03
And we want to compare a hollow sphere with a solid sphere.
02:07
So it's hard to draw the 3d images, but let's just draw it as like a disk here.
02:12
Here's the hollow...