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Flashcards in biomechanics (chapt.11) Deck (15):


Abasemet of human body based on biological sciences and engineering mechanic. Mechanics is the study of forces and their effects on masses


Newtons 3 laws

1.Every object in a state of uniform motion tends to remain in that state of motion unless as external force is applied to it

Unbalanced force acting on a mass changes its motion condition. The second stats that force of ears mass m multiplied by acceleration a: F=M*A Third makes it clear that force exertion requires the presence of an equally large counter force

2.The relationship between an objects's mass m, its acceleration a, and the applied force F is F=ma. Acceleration and force are vectors (as indicated by they symbols being played in slant bold font in this law the direction of the force vector is the same as the direction of the acceleration vector.

3.For every action there is an equal and opposite reaction.


Biomechanics Models

mathematical models of the mechanical properties of the human body. Allow predict the stress levels on specific musculoskeletal components quantitatively with established method of physics and mechanical engineering.

Help to design jobs/workstations and avoid hazardous job situation


Understanding Human Body Biomechanics

skeletal system, joints, muscular system

Joint types (fibrous, cartilaginous, synovial)
-saddle,hinge,gliding saddle, ball and socket


Muscular system

the muscle are generators of internal force the convert energy chemically stored in the body into mechanical work.

-extrinsic muscles
-intrinisic muscles

-tendons-connective tissue resembling a tough cord or bans and always part muscle, usually forming an attachment of muscle to bone

-ligament-connective tissue resembling a tend except a ligaments attaches bone to bone

-bursa-a structure resembling a collapsed bag with cellphone-thin walls whose inner surface are extremely smooth, moist, and slippery


Muscle Endurance and fatigue

reduced by rest and maximal endurance just a few seconds 50% of tension is available for about one minute but less than 20% can be applied for long endurance periods


Single segment planner static model

load weight can be calculated with the equation

W is the weight of object measured in newton's (N)
M is the moss of object measured in kilograms (KG)
G is the gravitational acceleration (a constant of 9.9 m/s2


Occupational biomechanics

study of the physical interaction of workers with their tools, machines, and materials so as to enhance the worker's performance while minimizing the risk of musculoskeletal disorders


Skeletal system-vertebral column

skull,vertebral column,pelvis, sacrum,



In Cartilaginous joints the bones are attached by cartilage . These joints allow for inly a little movement, such as in the spine in the spine or ribs.



connect bones without allowing any movement. The bones of the skull and pelvis are held together by fibrous joints.



Synovial joints allow for much more movement than cartilaginous joints. Cavities between bones in synovial joints are filled with synovial fluid. This fluid helps lubricate and protect the bones. Bursa sacks contain*the synovial fluid.


Static contraction strength

an isometric muscle contraction generate the static condition. During isometric effort there is no change in muscle length.
Dynamic contraction strength


muscle fatigue

is defined operationally as a state of reduced physical ability which can be restored by rest


muscle endurance

a maximal exertion can be maintained for just a few seconds;50% of tension is available for about one minute; but less than 20% can be applied for lining endurance periods