I would like to create a shape similar to this, and I was thinking of using a line and then bending it along a circle, but I'm not sure how to do that.
- Draw a circle.
- Press P and click on the actual circle in 2 places (see below). The cursor changes when you're directly above the line.
- Press A and drag to select one of the points you added then hit DEL to remove that.
- With this shape selected, in the Stroke panel increase the weight value until it looks thick enough and click the 'Round Cap' option.
- Hit R and drag around to rotate the object and adjust the gap position.
- And this is how you add a gradient: https://graphicdesign.stackexchange.com/a/30344/62949
Create a circle, and then add some extra anchor points to it (Object > Path > Add Anchor points and do it a few times)
(You can also just add the extra points via the Pen Tool P)
Then use the Direct Selection Tool (A) to select and a delete a few anchor points from one corner:
Now apply a thicker stroke to it and go to Window > Stroke (Ctrl+F10);
set the Cap to rounded
Now just apply a gradient to it.