인체의 움직임과 통증이해 핵심요소는 friction force and friction heat. 오늘의 big aha!

[문형철]

인체는 움직인다. 

움직임을 가진 물체는 두가지 문제가 발생한다. 

녹스는 것과 마찰열!!

그래서 마찰력과 마찰열은 중요한 개념이다. 

friction force and friction heat

인체는 기본적으로 dry friction은 없다. static friction도 없다.

항상 fluid friction, skin friction, internal friction, belt friction의 기본을 바탕으로 dynamic(kinetic) friction이 있다. 

비정상적인 friction heat를 유발하는 인체의 문제들이 통증의 원인이다. 

그것들이 무엇인가? 

Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction:

- 마찰은 단단한 표면, 유동액 층, 물체의 미끌림사이에서 상대적으로 저항하는 힘을 말함. 몇가지 마찰의 형태가 있음. 

• Dry friction resists relative lateral motion of two solid surfaces in contact. Dry friction is subdivided into static friction between non-moving surfaces, and kinetic friction between moving surfaces.

건조마찰 - 두개의 단단한 표면이 부딛히면서 저항하는 것. 건조마찰은 움직이지 않는 면사이의 정적인 마찰과 움직이는 면 사이의 운동학적 마찰이 있음. 

• Fluid friction describes the friction between layers within a viscous fluid that are moving relative to each other.^[1][2]

유동마찰 - 점성의 유동액내에서 마찰이 발생하는 것

• Lubricated friction is a case of fluid friction where a fluid separates two solid surfaces.^[3][4][5]

윤활마찰 - 유동액의 경우에 발생하는데 두개의 단단한 면이 분리되어 발생하는 마찰

• Skin friction is a component of drag, the force resisting the motion of a solid body through a fluid.

피부마찰 - 피부면에서 발생하는 마찰

• Internal friction is the force resisting motion between the elements making up a solid material while it undergoes deformation.^[2]

내장 마찰 - 움직임에 저항하는 마찰.

• Belt friction

  Main article: Belt friction

  Belt friction is a physical property observed from the forces acting on a belt wrapped around a pulley, when one end is being pulled. The resulting tension, which acts on both ends of the belt, can be modeled by the belt friction equation. In practice, the theoretical tension acting on the belt or rope calculated by the belt friction equation can be compared to the maximum tension the belt can support. This helps a designer of such a rig to know how many times the belt or rope must be wrapped around the pulley to prevent it from slipping. Mountain climbers and sailing crews demonstrate a standard knowledge of belt friction when accomplishing basic tasks.

  Kinetic friction

  Kinetic (or dynamic) friction occurs when two objects are moving relative to each other and rub together (like a sled on the ground). The coefficient of kinetic friction is typically denoted as μ_k, and is usually less than the coefficient of static friction for the same materials.^[17][18] However, Richard Feynman comments that "with dry metals it is very hard to show any difference."^[19]

  New models are beginning to show how kinetic friction can be greater than static friction.^[20] Kinetic friction is now understood, in many cases, to be primarily caused by chemical bonding between the surfaces, rather than interlocking asperities;^[21] however, in many other cases roughness effects are dominant, for example in rubber to road friction.^[20] Surface roughness and contact area, however, do affect kinetic friction for micro- and nano-scale objects where surface area forces dominate inertial forces.^[22]

When surfaces in contact move relative to each other, the friction between the two surfaces converts kinetic energy into heat. This property can have dramatic consequences, as illustrated by the use of friction created by rubbing pieces of wood together to start a fire. Kinetic energy is converted to heat whenever motion with friction occurs, for example when a viscous fluid is stirred. Another important consequence of many types of friction can be wear, which may lead to performance degradation and/or damage to components. Friction is a component of the science of tribology.Friction is not a fundamental force but occurs because of the electromagnetic forces between charged particles which constitute the surfaces in contact. Because of the complexity of these interactions, friction cannot be calculated from first principles, but instead must be found empirically.

[공재철]

http://en.wikipedia.org/wiki/Friction