How to Spin Fast by Mark Lenzi
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How to Spin Fast by Mark Lenzi We already know that applying a force to an object creates a reaction that is opposite and equal to the force applied. How than do we create a force in a circular motion. This is easy to accomplish! First, you must exert the maximum force possible to get the maximum reaction. To understand this easily, think of a baseball player at bat. If this batter wants to hit a home run, then he will have to swing fast and in a large arc to achieve the velocity necessary to hit the ball out of the park. If that batter swings the bat halfway and then hits the ball, then he has only applied half the force necessary to hit the ball as far as he possibly can. He must swing the bat all the way around to gain the maximum velocity and force to cause a reaction on the ball to fly out of the park. This is a simple analogy for what a diver must do to achieve the maximum velocity necessary for him or her to cause a maximum action on the board that will cause a reaction on the diver's spin. The diver must achieve this force before his feet leave the board. Remember the Voyager spacecraft? If the diver leaves the board before he completes his arm throw than all the force after he leaves the board will act in an opposite direction of his throw and that direction is the opposite of the way he wants to spin. The diver's feet will then come towards his hands. This is not an effective way to spin. Here is a question that will test your knowledge of how this works. A diver is on the ten meter platform with his hands above his head and he steps off of the platform. He is now falling toward the water. If he then throws his arms forward and down, then what will happen? Will he somersault? The answer is no! He will not somersault. His feet will act in the opposite direction of his hands. This will cause his feet to come up toward his hands in a pike position. Think of a cheerleader. When a cheerleader wants to jump up and do a pike she will jump up and then throw her arms down which causes her feet to come up. To get her feet back under her before she hits the ground she will throw her hands back up. This is precisely what happens to a diver when his feet leave the board or platform. Any motion or force that is applied after a diver leaves the board will only act in the opposite and equal direction that it was applied. Coaches need to understand this basic principle of action and reaction to effectively teach their athletes and correct their athletes mechanics. If a coach doesn¹t understand this basic principle then how can that coach have any credibility with his athletes. In any other profession people are required to know what they are doing to effectively do their job. How then can a diving coach instruct divers if he doesn¹t understand this basic principle of physics? After all, diving is nothing but applying physics to an athletic endeavor. If I were an airline pilot you would expect me to know how to fly a plane, right? Athletes expect their coaches to know what they are doing as well. Coaches should take pride in their profession and give their best to their kids by being as thoroughly educated as possible. Forward Somersaults Now that you know how this basic principle works, let us apply it to a forward somersault. A diver should be able to reach all the way up to vertical while the board is at it¹s lowest point. If a diver is unable to get to this point, then the rest of this explanation will do no good. Timing is everything in diving! You must be able to get to each specific point or the timing and action will be flawed. We have now established where a diver¹s arms should be at a specific point in the takeoff. What should happen next? God bless Isaac Newton! Isaac Newton¹s second law of motion comes into play.Newton's second law of motion states that force equals mass multiplied by acceleration or F=ma. This law is the heart of achieving the necessary force to complete a somersault. The force in this equation is the vector sum total of all the energy that has been stored up in the hurdle and throw to come. If all of these forces add up to zero, then the object and or diver will not accelerate and or somersault. This is what happens when a diver leaves the platform with his arms above his head and then throws on the way down. His legs come up. If you have forgotten this principle then go back and reread the beginning of this chapter. Now, what can a diver do to maximize Newton¹s law? The diver should throw, with straight arms, down in an large arch as far as possible and as quickly as possible before leaving the board. We have already seen the action and reaction that occurs after a diver leaves the board. We have also seen how a baseball player hits a home run. Therefore, it is imperative for a diver to get his arms all the way down before his feet leave the board. The further down the diver gets his arms, the more somersault that is generated. A diver should be able to see his hands just over his feet as he is leaving the board. If this position is accomplished then the diver has no other recourse than to spin at a fast rate. I often saw my hands just over my feet as I was leaving the board. And I could spin pretty expeditiously! Make sure that your diver throws his hands, arms, head, and then chest down into the somersault. Any other variations of this sequence causes a diver to get stuck at the top and or cut off the board. This is the most effective way of generating speed and power in the somersault. The image of this sequence is one in which each component of the throw adds power to the somersault. As the hands go through, the arms add more power. As the arms go through, the head adds even more power. Get the picture? It is like pulling a spring back more and more until it fires away. Is this the last thing a diver should do? The answer is a resounding no! The amount of energy that has been applied to the somersault is set and is constant as the diver¹s feet leave the board. How can we then make ourselves spin even faster? The answer is Kepler's law! Kepler's Law Kepler¹s law was used to explain how the planets spin around the sun. Isaac Newton then used Kepler¹s laws to explain the science of mechanics. We can use this law to easily explain how to spin quickly in a somersault. Kepler's law states that the speed of an object is inversely proportional to it's distance from the center of the radius at which it is spinning. There is centripetal force applied, but without torque. The quantity of energy conserved in this situation is called the angular momentum. Simply put this means that as a diver gets into a tighter and tighter tuck and or pike, the speed at which he spins will increase. This can be seen in figure skating too. When a skater pulls his or her arms in tighter to his or her body, the speed of the twist increases. This can be applied to somersaults and twists. Here is an experiment to better explain what happens using Kepler's law. Take a glass tube, a string, and a ball. Attach the ball to the end of the string and run the string through the tube. Spin the ball around in a circle. As you do this, pull the string slowly through the tube so the radius of the circle of the spinning ball gets smaller. What happens to the speed of the ball? It gets faster and faster as the radius decreases. You have now seen how this law of conservation of angular momentum works. Let us apply it to a diver. Your diver is just leaving the board. He or she will travel in a specific trajectory for a specific amount of time from the board to the top of the dive and then down to the water. Generally, this usually lasts for about two seconds or so. This is why a diver must reach all the way up or he or she will travel to far from the board and will not be able to score well and or make their dive. Because the trajectory and time of the flight of the dive have been established, the diver should immediately squeeze his or her tuck to decrease the radius as much as possible and as soon as possible. This also allows the diver to spin on the way up. I have seen too many divers that jump very high and wait until they are at the top of their dive to get into a nice tight tuck. Why wait? You know that you have established a certain trajectory and time of flight. Take advantage of the limited space and time by spinning on the way up.