21. In either case, the rotating observers see circular motion and require a net inward centripetal force : 22. In that case the centripetal force is provided by tension in the string, not by gravity. 23. The present theory concerns only the low energy lightning ball form, with centripetal forces and surface tension. 24. This force is directed inward, along the direction of the string, and is called a centripetal force . 25. This pressure gradient provides the centripetal force necessary for the circular motion of each parcel of air. 26. This pressure gradient provides the centripetal force necessary for the circular motion of each parcel of water. 27. The parabolic shape is because the centripetal force is proportional to the square of the tangential speed. 28. The circular stepping pattern also builds up centripetal force , allowing the practitioner to maneuver quickly around an opponent. 29. All of these changes exemplify the continuing trend of centripetal forces that augmented the power of the regime. 30. This is a centripetal force distribution.
