Forces and Geometry in body Structure
When we’re looking at how things work or move, we try to identify the force that’s responsible. So when a flying ball falls to the ground, we say “Aha! That’s the force of gravity.” But it’s very rare to find only one force acting on something. Most of the time, there are several different forces working at once, all pulling or pushing with different strength, often in completely different directions. The effects of all these forces add together or subtract from one another to produce a resultant force.
How to calculate the resultant force? The simple way is to utilize the basic principles of geometry.
Sometimes all the forces are exactly in balance—their effects cancel one another out. If you look at a giant suspension bridge, it’s not going anywhere or changing its shape, so you might think there are no forces acting on it. Wrong! There’s the weight of all the cars driving across it pulling downward, plus its own weight. So why doesn’t the bridge tumble into the river? The force of gravity pulling down on the bridge is exactly balanced by tension (pulling forces) in the suspension cables tugging it back up again. Because all the forces on a bridge are equal, the bridge itself goes nowhere—so it’s safe for the cars to drive across.
The bridge design will consider the worst condition — the heaviest trucks at the center of the bridge.That means all parts of the bridge work together to take most forces without any damage — this is like the moment of impact zone for golf swing. This is the project of spaghetti bridge competition.
The other example is the load force hanging on the top of the crane machine: we can figure out the force applied on the boom if we know the weight of the load by geometry.
Athletes’ bodies experience these forces in many ways. The forces experienced by playing different actions on different sports, because of their own movements or because of different equipment they use.
During golf swing, there are many internal forces created: the torsion force is created on the torso during backswing; the compression force is created on the knees and hips as the lower body straightens up during the impact zone.
For golf swing it is more complicated because the centripetal force at the impact is not vertical with ground like the load force on the crane machine. So it needs solid geometry to figure out the three forces along three directions ( show in two 2-D graphs).
The vertical pulling force: the lower body’s jump and erection at hips just like the action of deadlift , we can see these actions from the swing of Tiger Woods and Rory Mcilroy.
The horizontal pulling force: the square feet position and controlling heels down & behind can make the body at the best position to pull arms horizontally; we can see these positions from the swing of Sergio Garcia and Kenny Perry.
The lateral pulling force: The lateral movement of the pelvic is a basic action of creating lateral pulling force. Besides, if the torso’s turning is leading the shoulder and the arms just following, the lag position along the lateral direction will happen naturally at the impact .
Creating bigger forces with actions of body structure
Human body is a perfect structure and human movement is actually very complex. Movement is a change in place, position, or posture in relation to the environment. Movement happens only when different body systems, such as the skeletal system, cardiovascular system, neuromuscular system, and the muscular system, work together to create the force. (By physics, any item can not move without a force acting on it. )
Thanks to human ingenuity. With clever tools help, we can make our arms and legs move much bigger and heavier weights. Simple tools include levers, such as wrenches. They work by allowing your body to produce more force than it can make alone.
So if you use a wrench to turn a rusty nut, you’re using the power of a lever to magnify a force: the longer the lever, the more the force at the center is magnified and applying less force at the edge. By the same way we can create more force ( and high speed) at the club head by body’s action working together with the club.
