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______: The branch of physics that deals with the action of forces on the body
______: The interdisciplinary science that applies the principles of mechanics to the study of biological systems.
______: Studies the actions of forces in producing or changing the motion of masses (objects)
- 1. Mechanics
- 2. Biomechanics
- 3. Kinetics
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______: an agent that produces or tends to produce a change in the state of rest or motion of an object
Force
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_______: A force that exists as two objects, in contact, move over one another
Friction
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Force is a ______ quantity: has both magnitude and direction.
______ quantity has only magnitude.
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_______: of the arrow identifies the pointof application of the force on the body.
_____: of the arrow identifies direction of the force
______: of the arrow identifies: the line of pull; (direction) of the force the magnitude of the force
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_____ of forces: resultant effect of several forces.
_____ of forces: to separate a compostion of forces into several component forces.
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_____ _____: perpendicular distance from the line of actoin of the force to the axis of motion. The perpendicular distance is used to calculate torque.
Moment Arm
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_____: object's resistance to change.
Inertia
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If tow things of different masses are moving at the same speed, it takes greater force to change the motion of the (larger or smaller) body.
larger: inertia is proportional to mass
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Law of _____: a body remains at rest or in motion unless acted on by an external force.
Inertia
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_____ Equilibrium: velocity is zero
____ Equilibrium: velocity is constant but not zero
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A ______ is needed for humans to overcome intertia to stop or start movement.
muscle contraction (Force)
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Newton's 2nd law states that:
F= MA
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When one object applies a force to a second object, the second object simultaneously applies a force equal and opposite in direction to the first object?
Newton's 3rd Law: Law of Reaction
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In regards the Law of Reaction: the interaction pair is referred to as the _____ forces. And the reaction forces bear names that are the inverse of each other.
Reaction
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____ of _____: hypothetical point of a body about which every particle of mass is equally distributed. The object is perfectly balanced and is where the force of gravity is perfectly balanced.
Center of Gravity
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____ of ____: represents the action line and direction of the force of gravity.
Line of Gravity (can be the same as the gravity force vector)
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For humans, the theoretical center of gravity is anterior to ____.
S2
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Describe the 4 factors that affect stability:
- 1. Height of the COG
- 2. Area of the Base of Support
- 3. Location of the Line of Gravity
- 4. Weight of the Object
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_______: force that exists whenever two objects touch and one is made to slide/move over the other.
Friction
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_______ force system: two or more forces acting at a common point of application but in divergent directions.
Concurrent force system
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_____ Muscle: a concurrent force system consisting of 2 or more portions of one muscle, or 2 muscles with a common point of attachment.
Divergent muscles
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______ force system: force applied to identical points on opposing objects and go in opposite directions.
Linear Force System (tug of war)
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______ of Forces: process of finding the net effect, or resultant force of all forces acting on a common point.
Composition
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______ force system: 2 or more forces act on the same object but at some distance from each other and have action lines that will not intersect (parallely)
Parallel
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___ class lever: axis is between effort force and resistance.
___ class lever: resistance between axis and effort force.
___ class lever: effort force between axis and resistance.
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____ ____: measure of the efficiency of a lever.
- Mechanical Advantage
- M Ad= EA/RA
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If: M Ad > 1 then ___ >____.
EA is > RA
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In whch class lever do most muscles contract concentrically? As what force?
3rd class, as the EF
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In which class lever do most muscles contract eccentrically? As what force?
2nd Class, as the RF (due to improved mechanical advantage)
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Human movement is mechanically inneficient. Why?
EA is always smaller than the RA; decreased M adv., need to generate a greater force to move segment.
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___ class levers: designed for increased speed and greater ROM of distal end of lever through space.
3rd
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___: shortest distance between the force's line of action and the joint axis.
Moment arm
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A lever are is a ____ distance from the axis to the point of attachment of the force.
The moment arm of a force ____ distances as the lever moves and the anle of application of the force changes.
- fixed distance
- changes distances
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____= force times displacement.
Work
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_____ force component: portion of a force that is applied perpendicular to the lever.
Rotary
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_____ force component: portion of a force that is applied parallel to the lever.
If applied in the direction of the joint, it is referred to a ____ component.
If applied away from the joint, it is referred to as a _____ component.
- Translatory
- compression
- distraction
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Describe 3 ways to increase torque advantage of an externally applied force.
- 1. increase magnitude of the external force
- 2. apply the external force perpendicular to the lever
- 3. increase the distance between the external force's point of application and the joint axis.
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