# UCM and Ovals

1. Oct 19, 2005

### WarpDrive

I understand Uniform Circular Motion and an object's acceleration while in UCM. But, how does that change when an object moves around an oval? Does the acceleration vector point more towards the line tangent to the oval than just to the center? What if the object itself has increasing or decreasing speed. This should change the magnitude of the velocity, I assume, but how would that affect the direction?

Thanks!

2. Oct 20, 2005

### Staff: Mentor

An object moving with constant speed in a circle will have an acceleration always perpendicular to its velocity; same for the object moving with constant speed in a oval. Of course, in the case of the oval, that direction will not always point to the center of the oval.

If the speed changes as well, then the acceleration will also have a tangential component.

3. Oct 20, 2005

### Staff: Mentor

If you're thinking of something like a planet moving in an elliptical orbit around the sun or some other body, then the acceleration vector always points towards one focus of the ellipse, where the sun is located. The gravitational force exerted by the sun keeps the planet in its orbit, and that force always points towards the sun. The planet's acceleration must also point in that direction, unless some other body is also exerting significant gravitational force on it.