Have you guys seen the new fad among today’s teenagers? They have that three sided thing that keeps on spinning; pretty much like a top. It is called a fidget spinner. Seems like the beyblade that got famous about a decade ago. Doctors say that it relieves stress as well; hence the ‘fidget’ in the name. However, unlike a typical top, this spinner rotates around something at the centre. The actual centre from which we hold the spinner, is stationary. How is this possible? Let’s look into the physics of this mystical new toy.
To understand the physics, let’s take the example of a hammer thrower in Olympics. You would see that the athlete takes a few rounds for momentum before throwing the hammer. Now the distance of the throw depends on the speed of release and the angle at which it is thrown. As in case of a fidget, angle doesn’t matter, we’ll look at the speed. In a fidget spinner, the speed is determined by how fast our hand pushes the spinner. Thus to optimise this, you can only move your hands/fingers faster. Now even though it starts at a swift speed, a fidget seems to spin for much longer than say a beyblade or a top at the same initial speed.
Well imagine if the hammer thrower had a table tennis ball attached to the end. Obviously, it won’t go as far. The reason is more air friction and lesser weight. The ability of the spinner to spin longer depends on what we call a centripetal force. This force is directly proportional to the mass of the object, to the square of the initial speed and inversely proportional to the radius of object. So the heavier and bigger the spinner is, the longer it will rotate. Note that we are assuming that our bottleneck would always be the speed at which we hit the spinner and the weight of the spinner will never be more than what we can rotate easily. .
The final aspect would be friction. The TT ball was stopped by air friction. A top gets stopped by the friction between the floor and the tip along with the air friction. But due to the shape of a fidget spinner, air friction is reduced a lot. And if you open the middle part where you hold the spinner, you’d see a ball bearing in the middle. Ball bearing are wonderful inventions that are used to reduce friction between rotatory objects. In case of ball bearings, the small metal balls, rotate between both the surfaces holding the metal ball. Because of the spherical shape of ball bearings, the contact area is very less. This reduces the friction to a huge extent hence enabling the fidget to spin longer.
Finally coming to the biology, fidget spinners are claimed to help ADHD (Attention Deficit Hyperactivity Disorder) and autistic patients in terms of concentration. Fidgeting has always been seen as a sign of nervousness, boredom or stress. Typically people used to fidget with their pens, rings or hair. This was seen as a sign of under-confidence. With the advent of the fidget spinner, fidgeting became more sophisticated and acceptable. Shaking your leg or playing with your hair wasn’t seen as a pleasing gesture, but rotating a fidget spinner is seen slightly classier. Along with it, it helps people with ADHD concentrate as it provides constant stimulation. It works on the same logic as how some people prefer having background music while reading. The music is light enough to not distract them, but constant enough so their mind doesn’t wander and focus on the reading only.
Now that we know how Fidget spinners work; what do you think we’d require to make the best fidget spinner. Well, my best guess would be a huge fidget spinner probably made by a heavy metal like gold with a well lubricated ball bearing setup. We’d need strong hands by the way!!!