00:01
We're looking here at a diagram of a marble in a spherical bowl.
00:06
The first thing we're asked to do is label the marble's equilibrium position.
00:12
And the equilibrium position is going to be the position that the marble would be in if it were at rest, if it weren't moving at all.
00:21
And that's going to be at the bottom of the bowl.
00:23
So the bottom of the bowl, that's going to be the equilibrium position.
00:34
Next, we're asked, what would you expect to happen if you push the marble away from equilibrium? and you can imagine if you push it to the right, it's going to fall back to the left.
00:47
If you push it to the left, it's going to fall to the right.
00:51
So if you displace it from equilibrium, it's going to move towards equilibrium.
01:13
We're asked, why do you think the marble behaves this way? and we're given the hint of adding a free body diagram to each marble.
01:23
And i like that idea, so i'm going to go ahead and do it, but i'm going to redraw the free body diagrams below.
01:30
So when we're at the equilibrium position, the forces that act on the marble are the gravitational force, which is straight downward, and the normal force, which is straight upward...