PE BioMech

Linear motion:

  • Movement of an object or body in a straight line or curved path

 

Angular motion:

  • Movement of an object or body around an axis (rotational)

 

General motion:

  • A combination of linear and angular motion (most human movement)

 

Projectile motion:

  • The flight path of an airborne body or object that can be manipulated by three main factors

 

Projectile:

  • An airborne body (e.g. person) or object (e.g. ball)

 

Air resistance:

  • Force acting on a projectile that affects the horizontal distance of a projectile

 

Gravity:

  • Force acting on a projectile that affects the vertical distance of a projectile

 

Speed of release:

  • The rate at which a projectile is released into the air

 

Angle of release:

  • The angle at which a projectile is released into the air

 

Height of release:

  • The starting height at which a projectile is released into the air

 

Mass:

  • The measure of the quantity of matter found in an object or body

 

Inertia:

  • The reluctance of a body to change its state of motion

 

Force:

  • A push or pull from one body with mass to a second body, causing it to accelerate, decelerate or change direction

 

Distance:

  • The amount of ground an object covers throughout its motion (or degrees it rotates)

 

Displacement:

  • A body or object's overall change in position from start to finish (contains a direction)

 

Speed:

  • Distance / time - the rate at which an object or body is moving from one location to another.

 

Velocity:

  • Displacement / time - another rate at which an object or body is moving from one location to another (contains a direction, unlike speed)

 

Acceleration:

  • The rate of change in velocity of an object or body

  • An indicator of whether an object is speeding up, slowing down or staying the same (can be +velocity, -velocity or zero)

 

Momentum:

  • The amount of motion that an object or body possesses

  • Linear = Mass x Velocity

  • Angular = Angular velocity x Moment of inertia.

 

Moment of inertia:

  • The reluctance of a body or object to rotate

  • (radius^2 x mass) of object that is rotating

 

Summation of forces:

  • The correct timing and sequencing of body segments through a range of motion

  • Body parts, sEquence, Stabilise, Timing (BEST)

 

Impulse:

  • The change in momentum of a body

  • (Impulse = force x time)

 

Torque:

  • A force that causes an object to rotate

 

Friction:

  • Occurs when two surfaces come into contact

  • Successful skill execution may require high or low amounts of friction

 

Lever:

  • A structure made up of a rigid bar, an axis, force input and resistance. Used in human movement to manipulate other objects (e.g. projectiles)

 

Axis:

  • The point of rotation for a lever (e.g. an elbow)

 

Range of motion:

  • The full extent (in degrees) that a lever can move through its potential arc

  • The larger the ROM, the greater the speed advantage

 

Mechanical advantage:

  • The measure of a lever's ability to produce speed or force (MA = length of Force arm / length of resistance arm)

  • The lower an MA, the greater range of motion and speed that the lever can produce

 

Third class lever:

  • where the force (effort) is applied between the axis (fulcrum) and the resistance (load)


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Newtons first law:

  • An object in motion stays in motion unless acted upon by an unbalanced force

 

Newtons second law:

  • An object will accelerate proportionate to the force applied and inversely proportionate to its mass

  • Force = mass x acceleration

 

Newtons third law:

  • Every action has its equal and opposite reaction

 

Equilibrium:

  • When all opposing forces are balanced, can be static (stationary) or dynamic (whilst moving)

 

Stability:

  • The degree at which the body resists changes in equilibrium (this can be manipulated)

 

Balance:

  • The ability to maintain or control equilibrium (this can be trained)

 

Base of support:

The area of an object that is in contact with a surface (greater BOS = greater stability)

 

Line of gravity:

  • Imaginary line that travels through the centre of gravity into the middle of the base of support (LOG closer to middle of BOS = greater stability)

 

Centre of gravity: 

  • The central point of an object that weight is evenly distributed around (lower COG = greater stability)