# Circular motion and vertical circle

1. Oct 18, 2007

### MIA6

Now I am learning Uniform Circular motion, but I don't know what do horizontal circle and vertical circle mean? I think they must be very different in solving problems. Hope you can tell me, thank you.

2. Oct 18, 2007

### Staff: Mentor

A horizontal circle generally means that the plane of the circle is horizontal (the axis is vertical). A vertical circle is the opposite.

3. Oct 19, 2007

### clustro

a horizontal circle will have the force of gravity parallel to the axis of rotation, while a vertical circle will have gravity perpendicular.

The tension in the string will vary at different positions along its path of travel in the case of a vertical circle. (Maximum at the bottom, mv^2/r + mg, minimum at the top, mv^2/r - mg).

I think at least. Please correct me if I'm wrong

4. Oct 19, 2007

### SpicyRamen

Wouldn't the tension in the string be (F+mg) at the bottom and (F-mg) at the bottom? When your at the bottom you need a greater force to work against gravity to pull the weight up, but when your at the top gravity helps you.When the weight is on the side it's force is equal( Parallel?)

5. Oct 20, 2007

### Staff: Mentor

Yes.

In the case of an object on a string being spun at constant speed in a vertical circle, you are correct.

6. Nov 6, 2007

### Ashwath

Technically it isn't possible to whirl a bob in a perfect horizontal circle - see if you can figure out why.

7. Nov 6, 2007

### Staff: Mentor

Why not? (The string won't be horizontal, but the circular path can be.)