1. KINESIOLOGY دکترامیر هوشنگ واحدی متخصص طب فیزیکی و توانبخشی قسمت 4

3. Mechanical Advantage 1.Levers 2.Pulley system. 3.Wheel and Axle 4.Inclined Plane

4. Types of Levers a. First-class: fulcrum between effort & load; scissors, seesaw, crowbar

5. b. Second-class: load between effort and fulcrum; wheelbarrow, standing on toes; not common in body; strength

6. c. Third-class lever: effort between load and fulcrum; speed, mechanical disadvantage; most skeletal muscles

18. Angle of Pull

46. FORCE -usually defined as mass times acceleration (F=ma), or as the entity which tends toproduce motion, or to halt or change direction of motion. More simply put, force can be defined as a push or pull (exerted by one object or substance on another). Forces can be external (gravity, speeding automobiles, football players) or internal (the pull of amuscle, ligamentous resistance).

47. COMPRESSION -a loading mode in which collinear forces (forces which lie or act are acting in opposite directions to push the material together. The act of pressing together.

48. TENSION -a loading mode in which collinear forces acting in opposite directions tend to stretch or pull an object apart DISTRACTION -the act of pulling apart two surfaces. SHEAR -a force which acts parallel to a surface (normally a joint surface). Also known as a tangential force. TORSION -a force which tends to twist a body.

49. STRESS -the intermolecular resistance within a body to the deforming actions of an outside force...or, the force per unit area that develops within a structure in response to externally applied forces (tensile, compressive, shear, or rotary). STRAIN -deformation, or change in dimensions of a body as a result of the application of a force

50. VECTOR -a quantity specified by magnitude and direction. A FORCE VECTOR is a representation of a force in terms of its magnitude, line of application, direction, and point of application. MOMENT -the measure of the tendency of a force to produce rotation about a point or axis. (see TORQUE) MOMENT ARM -the shortest distance from an action line (the line through which a force acts) and the axis of motion.

51. TORQUE -a measure of the degree to which a force causes an object to rotate about an axis.Torque, therefore, applies to rotatory motion and is the product of a force applied perpendicular to (and at one end of) a lever arm and the distance of application of theforce from the axis of motion. That is, torque=force x length of moment arm.