______: 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)
______: an agent that produces or tends to produce a change in the state of rest or motion of an object
_______: A force that exists as two objects, in contact, move over one another
Force is a ______ quantity: has both magnitude and direction.
______ quantity has only magnitude.
_______: 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
_____ of forces: resultant effect of several forces.
_____ of forces: to separate a compostion of forces into several component forces.
_____ _____: perpendicular distance from the line of actoin of the force to the axis of motion. The perpendicular distance is used to calculate torque.
_____: object's resistance to change.
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
Law of _____: a body remains at rest or in motion unless acted on by an external force.
_____ Equilibrium: velocity is zero
____ Equilibrium: velocity is constant but not zero
A ______ is needed for humans to overcome intertia to stop or start movement.
muscle contraction (Force)
Newton's 2nd law states that:
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
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.
____ 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
____ of ____: represents the action line and direction of the force of gravity.
Line of Gravity (can be the same as the gravity force vector)
For humans, the theoretical center of gravity is anterior to ____.
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
_______: force that exists whenever two objects touch and one is made to slide/move over the other.
_______ force system: two or more forces acting at a common point of application but in divergent directions.
Concurrent force system
_____ Muscle: a concurrent force system consisting of 2 or more portions of one muscle, or 2 muscles with a common point of attachment.
______ force system: force applied to identical points on opposing objects and go in opposite directions.
Linear Force System (tug of war)
______ of Forces: process of finding the net effect, or resultant force of all forces acting on a common point.
______ 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)
___ 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.
____ ____: measure of the efficiency of a lever.
M Ad= EA/RA
If: M Ad > 1 then ___ >____.
EA is > RA
In whch class lever do most muscles contract concentrically? As what force?
3rd class, as the EF
In which class lever do most muscles contract eccentrically? As what force?
2nd Class, as the RF (due to improved mechanical advantage)
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.
___ class levers: designed for increased speed and greater ROM of distal end of lever through space.
___: shortest distance between the force's line of action and the joint axis.
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.
____= force times displacement.
_____ force component: portion of a force that is applied perpendicular to the lever.
_____ 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.
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.