Kinesiology of PE

systems w/ no motion; stationary

System in motion w/ acceleration

enables us to apply small force to move greater resistance

resistance/Force=MA

description of motion includes consideration of time, displacement, velocity, acceleration, and sace factors

study of forces  associated with the motion of a body

external & internal forces 

• Balance Multiple forces
• Increase force to overcome resistance
• Increase ROM & speed so resistance moves farther/faster than applied force
• Change direction of applied force 

• bar that turns about an axis of rotation/fucrum
  • bones

• Point of rotation which lever moves
  • fulcrum/axis
  • joints

• rotates lever about the axis (always close to muscle insetion)
  • Internal or external
  • Muscles

• weight/gravity
  • may vary in amount

• Produce balanced movement when axis is midway between force & resistance (seesaw)
• Triceps extension 
• Erector spinae extending head on cervical spine 
• FAR

• Produce forceful movement, since a large resistance can be oved by relatively small force
• Gastrocnemius & soleus inplantar flexing the foot to raise the body on the toes
• ARF
• FRA

• Produce forceful movement, since a large resistance can be oved by relatively small force
• Gastrocnemius & soleus inplantar flexing the foot to raise the body on the toes
• ARF
• FRA

• Produce speed & rane-of-motion
• Most common in hman body
• requires great deal of force to move small resistance
• Biceps brachii during elbow flexion
• AFR
• RFA

•Torque – (moment of force) the rotary effect of an eccentric force

•Force – a push or a pull

•Contributed by magnitude, direction, or point of application

•Measured in a Newton (N)

Types of Motion

• Linear motion- along a straight line
• Angular motion: rotation around an axis (usually joints)
• General motion: Combination of linear & angular motion (most common in human motion)

•Linear displacement - distance that a system moves in a straight line

•Angular displacement - change in location of a rotating body

•Speed - how fast an object is moving or the distance in a specific amount of time

•Velocity - includes the direction & rate of displacement

•Inertia - resistance to action/change

•In human movement - acceleration or deceleration

•Force is required to change inertia

•Acclerate/decelerate

•Change direction

•A body will maintain state of rest/constant velocity unless acted on by external force

•In other words: A body traveling w/ constant speed along straight path will continue its motion unless acted on by an external force that alters either the speed or direction of motion

•A change in the acceleration of a body occurs in the same direction as the force that caused it.

•Acceleration - the rate of change in velocity

•To attain speed in moving the body, a strong muscular force is necessary

•Mass - the amount of matter in the body

•affects the speed & acceleration in motion

•A force applied to body causes an acceleration of that body of magnitude proportional to the force, in the direction of the force, & inversely proportional to the body’s mass.

•In other words: When a ball is thrown, kicked, or struck w/ an object, it tends to travel in same direction of line of action of applied force.  The greater the amount of force applied, the greater the speed the ball has.

•For every action, there is an equal & opposite reaction. When one body exerts a force on a second, the second body exerts a reaction force that is equal in magnitude & opposite in direction on the first body.

•In other words: When a person leans w/ a hand against a rigid wall, the wall pushes back on the hand w/ a force that is equal & opposite to that exerted by the hand on the wall.

•Friction - force resulting from resistance between surfaces of two objects from moving upon one another

•To run, we depend upon friction forces between our feet & the ground so that we may exert force against the ground & propel ourselves forward

•Static friction - friction between two objects that have not yet begun to move

•Kinetic friction - friction occurring between two objects that are sliding upon one another

•Rolling friction - resistance to an object rolling across a surface

•Balance - ability to control equilibrium, either static or dynamic

•Equilibrium - state of zero acceleration where there is no change in the speed or direction of the body

•Static equilibrium - body is at rest or completely motionless

•Dynamic equilibrium - all applied & inertial forces acting on the moving body are in balance, resulting in movement with unchanging speed or direction

•Stability - To control equilibrium & achieve balance, stability must be maximized