Module 5—Circular Motion
Lesson Summary
In this lesson you focused on the solution to these questions:
- How do Newton’s laws explain the sensations during vertical circular motion, such as during a loop in a roller coaster?
- What forces come into play during vertical circular motion?
Free-body analysis can be used to understand the net inward force and tension acting on an object at the top and bottom of a vertical circular path. The tension, in turn, can be related to the sensations that a rider will experience while moving on a vertical circular path, such as those experienced on many roller coasters. At the top of the vertical circle, the tension acting is described by
, where g = +9.81 m/s2
If the tension reaches zero at the top of the arc, the object is in a momentary state of free fall. The speed at which this will occur is described by
At the bottom of the vertical circle, the tension acting is greater because it opposes the force due to gravity.
, where g = +9.81 m/s2
From this analysis, you are able to determine the acceleration acting on an object or rider at any point in the vertical circle, leading to a better understanding of the causes of the sensations experienced by riders when they are moving in vertical circles.
Lesson Glossary
tension: a stress that tends to stretch an object
vertical circular motion: motion in a circular path where one diameter of the circle is vertical
weightless: experiencing little apparent gravitational pull