Kines Unit 3

• Biomechanics


  Study of the mechanics as it relates to the functional and anatomical analysis of biological systems

  Necessary to understand movements
• Mechanics


  Study of physical actions of forces
• Statics


  Study of systems that are in a constant state of motion whether at rest with no motion or moving at a constant velocity without acceleration

  Involves all forces action on the body to be in balance (equilibrium)
• Dynamics


  Study of systems in motion with acceleration

  A system in acceleration is unbalanced due to unequal forces
• Kinematics


  Description of motion and includes consideration of time, displacement, velocity, acceleration, and space factors of a systems motion
• Kinetics


  Study of forces associated with the motion of a body
• Mechanical Advantage


  Load divided by effort

  Using a relatively small force/effort to move a much greater resistance
• Machines


  Used to increase mechanical advantage

  Balance multiple forces

  Enhance force in an attempt to reduce the total force needed to overcome a resistance

  Enhance range of motion and speed of movement so that resistance may be moved farther or faster than the applied forced

  Alters the resulting direction of the applied force
• Levers


  How humans move

  Cannot be changed, but they can be utilized more efficiently
• Lever


  Rigid bar that turns about an axis of rotation (fulcrum)
• Axis


  Point of rotation about which the lever moves
• Levers rotate about the axis as a result of ...


  Force or effort
• Bones represent...


  Bars
• Joints represent...


  axes
• Muscles contract to apply...

  force
• Axis (fulcrum)


  The point of rotation
• Point of force application (F) is...

  effort
• Point of resistance application (R) is


  the center of gravity of lever or location of an external resistance
• First Class Levers


  Produce balanced movements

  Axis is midway between force and resistance

  MA = 1

  Produce speed and range of motion when the axis is close to the force

  
• Third Class Lever


  Produce speed and range of motion movements

  Most common in human body

  Requires a great deal of force to move a small resistance

  Ex -> paddling a boat and shoveling

  MA = lesser than 1

  
• Anatomical leverage system can be used to...


  Gain a mechanical advantage

  Improve simple or complex physical movements
• Force Arm


  Perpendicular distance between the location of the force application and axis

  The greater the distance of the force arm -> the more torque produced by the force (torque arm is the axis)
• The longer the force arm...


  the less force required to move the lever if the resistance and resistance arm remain constant
• Shortening the resistance arm...


  allows a greater resistance to be moved if the force and force arm remain constant
• Wheels and Axles


  Used primarily to enhance range of motion and speed of movement

  Both complete one turn at the same time
• If the wheel radius is greater than the radius of the axle...


  the wheel has a mechanical advantage over the axle

  A relatively smaller force may be applied to the wheel to move a relatively greater resistance applied to the axle
• Pulleys


  Change the effective direction of the force application
• Center of rotation


  The point or line around which all other points in body move
• Quantity measurements


  Scalars

  Vectors
• Scalar Quantities


  Described by a magnitude or numerical value alone

  such as length, area, volume, mass, time, density, temperature, pressure, energy, work, and power
• Vector Quantities


  Described by both a magnitude and direction

  Such as acceleration, direction, displacement, force, drag, momentum, lift, weight, and thrust
• Displacement


  Change in the position of location of an object from its original point of reference

  
• Distance


  Actual sum of length of measurement traveled

  
• Angular Displacement


  Change in location of a rotating body
• Linear Displacement


  Distance that a system moves in a straight line
• Speed


  How fast an object is moving or distance that an object moves in a specific amount of time
• Velocity


  Includes the direction and described the rate of displacement
• Law of Inertia

  A body in motion tends to remain in motion at the same speed in a straight line unless acted on by a force

  A body at rest tends to remain at rest unless acted on by a force
• Muscle produce force to start, stop, accelerate (concentric), decelerate (eccentric), and change the direction of motion
• Inertia


  Resistance to action or change

  Resistance to acceleration or deceleration