Introduction to Biomechanics IV: Kinetic Movement Systems Flashcards
1
Q
Energy
A
- D: capacity to do work
- many types exist
- most interested in mechanical
2
Q
Mechanical Energy (ME)
A
-made up of PE and KE
3
Q
Kinetic Energy (KE)
A
- energy resulting from motion
- particularly dependent upon velocity
4
Q
Potential Energy (PE)
A
- capacity to do work secondary to position or form
- an object may contain stored energy because of height or deformation
5
Q
Strain Energy (SE)
A
- a form of potential energy
- mechanical energy due to deformation
- k in equation is proportionality constant
- delta x squared is distance material deformed
6
Q
Friction
A
- necessary for movement
- D: force that potentially exists whenever two objects come in contact
- exists when one object slides over another
- vector
- point of application is to both objects
- line of action is parallel to contacting surfaces
- direction is oppositional to potential movement of object to which it is applied
- magnitude exists only if there is attempted movement, depends on the Rx force on each object and nature of surfaces
- not dependent on contact area
- coefficient of static friction > coefficient of kinetic friction
7
Q
Coefficient of Friction
A
- describes the effect of different materials, roughness of contact surfaces
- the higher the coefficient the harder to overcome
- equation: Fx=mu x N
- N=normal force or force perpendicular to surfaces in contact
8
Q
Linear Force Systems
A
- D: forces applied in same direction along same action line
- results in translatory motion
- may be in same or opposite direction
- sum of forces equals 0 in equilibrium and do not equal 0 when in motion
- vectors up and right give + values
- vectors down and left give - values
9
Q
Concurrent Force Systems
A
- D: forces acting on one point but at different angles
- in same plane
- on same point
- not along same line
- net effect of all forces called resultant
- composition of forces allows for measuring resultant; solved graphically or via trigonometry
- effect of angle on magnitude of resultant (assume magnitude of forces remains constant)
- the greatest magnitude exists when forces act in the same line, in the same direction, and the angle between them is 0
- smallest magnitude exists when forces act in same line but in opposite directions and angle between them is 180 degrees
10
Q
Concurrent Force Systems in Muscle
A
- muscles act as vectors
- magnitude equals the resultant of all fibers in that muscle
- direction and action line in direction of muscle fibers
- point of application usually distal segment
11
Q
Concurrent Forces and Types of Muscle Structure
A
- muscles and muscle groups arranged with variety
- act individually or collectively
- produce very small movement or large, powerful movement
- shape and arrangement of fibers determine force generating capacity or shortening ability
12
Q
Concurrent Force Systems: Fusiform Muscles
A
- parallel muscle fibers
- fascicles run length of belly
- fibers run parallel to line of pull
- known for high amount of shortening, high velocity movement
- can shorten 30-50% of resting length
- ex: tibialis anterior, biceps brachii, rectus abdominis
13
Q
Concurrent Force Systems: Penniform Muscles
A
- fibers run diagonally to tendon running through muscle
- fiber force is different direction than muscle force
- feather shaped appearance
- secondary to short fascicles running at angle
- produce slower movements and more force
- trade off is increased physiologic cross-section leading to increased force
- ex: gastroc, deltoid, glute max
14
Q
Parallel Force Systems
A
- D: system where forces are parallel and lie in same plane but don’t have same line of action
- forces cause rotation around a stationary point
- resulting effect: rotation, translation, no motion
15
Q
Rotary Force Systems
A
- torque
- levors
- force couples
