| A | B |
|---|
| diameter | distance across a circle through its center |
| circumference | "perimeter" of a circle |
| radius | one-half the length of the diameter, distance from center to circle |
| centripetal | directed toward the center of a circle |
| centripetal | directed away from the center of the circle |
| tangential | at 90º angle to radiu at that point of the circle |
| circumference formula | 2∏r |
| 2∏ radians | 360º, one complete circle |
| centripetal acceleration formula | v^2 ÷ r |
| centripetal force formula | m(v^2 ÷ r) |
| orbital velocity | (2∏r) ÷ orbital period |
