There are certain laws that govern the universe and we must abide by those laws, as there is no negotiating them. Some of those are also referred to as laws, including the law of inertia, which states that an object at rest will remain at rest until it is acted on by an unbalanced force. In essence, it is saying that objects tend to stay at rest until something forces them to be in motion.
We see examples of this law in the natural world all around us, but it has also found its way into a rather unique mind test. This particular test shows us a series of gears and it gives us the direction of the first gear, but we need to decide the direction of the final gear. He uses this law, because each gear is going to put force on the next one, causing it to turn in a specific direction.
Some people are going to find this particular test rather easy to do but others may find it quite difficult. How long will it take you to do it, 20 seconds, 30 seconds, more? The answer can tell you a lot about yourself and your ability to think of things from a technical standpoint.