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Basic Biomechanics
Chapter 8:
| Question | Answer |
|---|---|
| Basic Biomechanics | taking the principles and methods of mechanics and applying the principles to the structure and function of the human body. |
| First Law (Law of Inertia): | An object at rest tends to stay at rest, and an object in motion tends to stay in motion (unless acted upon by an external force). |
| Second Law (Law of Acceleration) | F=mxa (force is equal to mass x acceleration). The amount of acceleration depends on the strength of the force applied to an object (it requires more effort to move a heavier object). |
| Third Law | (Law of Action-Reaction): for every action there is an equal and opposite reaction. |
| Force: | a push or pull action (the effort of a motion). No motion can occur without a force. Forces can be internal or external. |
| Torque: | the tendency of force to produce rotation around an axis (rotary force). Also the amount of force needed by a muscle contraction to cause rotary joint motion. |
| Stability | (when all torques acting on an object are even, a state of equilibrium). |
| Center of Gravity(COG) | : the balance point of an object at which torque on all sides is equal (where they intersect at a point). In the human body it is positioned at the 2nd sacral vertebrae (S2). |
| Base of Support(BOS): | the part of the body that is in contact with the supporting surface. |
| The lower the COG, | the more stable the object. |
| Stability increases | as the BOS is widened in the direction of the force. |
| The greater the mass of an object | the greater its stability |
| The greater the friction | between the supporting surface and the BOS, the more stable the body will be. |
| Levers | a ridged object that rotates around a fixed point (axis/fulcrum) when a force (effort) is applied. The force (muscular in the body) must overcome the load (resistance) in order to move. |
| First-class Lever: (FAR) | The axis is located between (middle) the force and the resistance, such as with nodding the head in the axis is the C1 vertebrae, the force is extensor muscles of the neck, and the load is the weight of the head. |
| Second-class Lever: (ARF) | The axis is at one end, the resistance is in the middle and the force is at the other end, such as with a wheelbarrow or when standing on your tip-toes in which the axis is the big toe, the force is the plantar flexors, |
| Third-class Lever: (AFR) | The axis is at one end, the force is in the middle, and the resistance is at the other end, such as with lifting a dumbbell in which the axis is at the elbow |
| Several conditions can change a lever | including adding a weight or changing the direction of the movement in relation to gravity. |
| Pulleys: | a grooved wheel that turns on an axle with a rope or cable riding in the groove. The purpose is to change the direction of a force or to increase or decrease its magnitude. |
| Wheel and Axle: | consists of a wheel, or crank, attached to and turning together with an axle used to increase the force exerted. The larger the wheel (or handle) in relation to the axle, the easier it is to turn the object. |
| Inclined Plane: | consists of a flat surface that slants. Although there is no example of one within the human body it is important in relation to wheelchair ramps |
Created by:
learntime101
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