Name:
Basic Sciences - Free Body Diagram: Hip
Description:
Basic Sciences - Free Body Diagram: Hip
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Duration:
T00H02M25S
Embed URL:
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Content URL:
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Upload Date:
2024-05-31T00:00:00.0000000
Transcript:
Language: EN.
Segment:0 .
ORTHOM8: Welcome to Basic Sciences. Today's topic is the free body diagram for the hip. This is a method of determining the forces and moments acting on the body by isolating the body part and ensuring that it is in static equilibrium. We make certain assumptions when we draw a free body diagram. Bones are rigid rods, joints are rigid, frictionless hinges.
ORTHOM8: No antagonistic muscle action. Weight of body is concentrated at the exact center of body mass. Internal forces cancel each other out. Muscles only act in tension. The line of action of a muscle is along the center of cross-sectional area of muscle mass. Joint reaction forces are assumed to be only compressive.
ORTHOM8: In single leg stance, one leg is assumed to weigh one sixth of the body weight, and the other 5/6 is through the center of mass. The moment arm is the perpendicular distance D from the hips, center of rotation to the force through the center of mass. The clockwise moment is D times 5/6 body weight. The force of the abductors is marked F, A, B, and the perpendicular distance to the hips.
ORTHOM8: Center of rotation is little d. The anticlockwise moment is d times f, a, b. Therefore, in a state of equilibrium, the anticlockwise moment is equal to the clockwise moment. Hence f, a, b times little D equals capital D times 5/6 bodyweight. If we assume a bodyweight of 60kg a distance capital D of 15 centimeters and a distance little D of 5 centimeters then f, a, b times 5 equals 15 times 500 newtons.
ORTHOM8: Hence f, a, b equals 15 times 500 over five therefore f, a, b equals 1,500 newtons.