The Ultimate Fidget Trick: Pencil Twiriling

Have you ever been sitting in class watching others spin their pencil around their finger effortlessly only to come up short when attempting to do it for yourself? Well, if you have, you are not alone. At one point, I was the kid who looked at those who could twirl their pencil around their fingers in wonder, trying to figure out the trick or learn the secret involved. In the end, it all comes down to physics. The most important principal of physics in this trick is balancing the torques in the angular motion that is required to successfully flip the pencil/pen around your finger. The first trick to determining how to successfully flip the pencil is to find the pencil's center of mass, which is the easiest point for pushing the object making it the easiest place to spin around the thumb in a balanced fashion. Once you find the center of mass of the object, it is important to place that point of the pencil on your middle finger, as that will be the finger that pushes the pencil. The next important piece to this trick is to place your thumb on a point of the pencil between your pointer and middle finger. This point is important to determine, as this is the pivot axis required to spin the pencil in one full circle, so there is no need to pick a point far from the center of mass, but it can't be right next to it either. The final part of the set-up is to touch the tip of the eraser end to your pointer finger so that you are holding the pencil in place between your middle finger (CoM), pointer finger (eraser end), with thumb in the middle. The next step requires some practice, but it involves pushing with your middle finger towards yourself at the same time as you push with your thumb away from yourself. These two seemingly contrasting directions of torque actually act in the same direction as angular motion, in a counterclockwise direction. The final trick is to catch once again by stopping the objects movement with your pointer finger, which allows for one full circle of pencil twirling. This trick may require a great deal of practicing, but it makes for a fun activity to pass the time or to show off to your friends.