Have you ever seen an athlete making a high jump like the above? You might have seen it, but do you know the name of this jump/flop? What's the physics behind this flop? How does it work? So, in this session, we will be finding the answers to these questions. So, without any delay, let's get started...
In the 1960s, Dick Fosbury, an American boy, tried to play almost every sport but wasn't good at any of them until he turned to the high jump at the age of 16. But when he couldn't compete against his strong athletes in his college using the standard high jump techniques of the time, Fosbury tried a different way to jump.
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| The standard technique for high jump |
Instead of jumping with his face towards the bar, bringing each leg over in the traditional straddle method, he jumped with his back towards the bar. Fosbury improved his method by over half a foot and left his coaches amazed by this strange new style of high jumping. During the next few years, Fosbury improved his high jump style, won the US National trials, and then got gold in the 1968 Olympics in Mexico with a record of 2.24 meters. By the next Olympics, almost all of the high jumpers adopted the new style of jumping called the Fosbury Flop.
What's the secret behind this Fosbury Flop? Well, the answer lies in a physics concept called the center of mass. For every object, we can locate the average position of all its mass by taking into account how the mass is spread around the object. In simple words, the center of mass is the place in which the whole mass of a body is concentrated. For example, the center of mass of a flat, rectangular object of uniform density will be in the intersection of both diagonals. We can find the center of mass of other objects by a similar process or by finding the object's balancing point, which lies just underneath its center of mass.
Like other objects, we humans also have a center of mass. When most people stand up, their center of mass lies near their belly, when you lift your hands up your center of mass moves upward, Well, the center of mass all the time as you move all day, based on your body position. You will be amazed to know that the center of mass can also move outside your body. When you bend forward, your center of mass is located below your bent belly, where there is no mass at all.
Now, look at the Fosbury Flop in the below video, and follow the center of mass of the jumper.
You can see that the jumper runs very fast so he can divert his horizontal velocity to vertical velocity and he jumps. In the end, just see the jumper's center of mass as his body bends backward. The center of mass is below the bar and that is the secret behind the jump. With the old jumping technique, the jumper had to apply enough force to lift his center of mass above the bar by a few inches to clear it. The Fosbury Flopper doesn't need to do so, the jumper can apply the same amount of force but raise his body much higher than before. That means that he can raise the bar so high that even when his center of mass can't go any higher, his arching body can.
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| Raise in height by using Fosbury Flop |
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Physics