Post on 27-Jan-2017
Y12 Physical Education AS90433
Bio mechanics
Biomechanics studies what makes a body move. It studies internal and external forces (remember a force is a push or a pull) that act on the body and other objects. It is possible to work out how your body should move in order to perform a task more efficiently. So for example we can use biomechanics to make you a better player!
Y12 Physical Education AS90433
Biomechanics Summary
Balance and StabilityNewton's LawsForce SummationProjectile MotionLevers
Y12 Physical Education AS90433
Balance and Stability
This is defined as the ability to hold or maintain a position in space
Stability generally depends on:The location of the centre of
gravity (COG) with respect to the base of support.
The direction of forces involved
Y12 Physical Education AS90433
Balance and Stability
Centre of Gravity is the point in the body at which all body parts are in balance.
In the anatomical position males generally have a higher COG than woman.
The body rotates around the COG
Y12 Physical Education AS90433
Four Main Principles of Stability
1. The closer the line of gravity is to the centre of the base of support, the greater the probability of maintaining balance
2. The broader the base of support, the greater the probability of maintaining balance.
Y12 Physical Education AS90433
Four Main Principles of Stability
3. Our balance is improved when we lower our Centre of Gravity in relation to the base of support. eg:
4. The further one part of the body moves away from the line of gravity, the probability of maintaining balance decreases unless another body part moves to compensate for it. eg.
Y12 Physical Education AS90433
Balance and Stability
We can further increase stability:
Increase Friction eg________Lean into an incoming Force eg______Increase Rotation eg________Increase Mass eg________
Y12 Physical Education AS90433
Newton’s Laws of Motion
Newton’s First Law: Law of InertiaAn object at rest tends to remain at rest
unless it is acted on by an external force.An object in motion tends to remain in
motion and to travel in a straight line with uniform velocity unless acted on by an external force.
Y12 Physical Education AS90433
Newton’s Laws of Motion
Newton’s Second Law: Law of Acceleration
When a force acts on a body, it’s resulting change in momentum is proportional to the force causing it and inversely proportional to the mass
Force = Mass x Acceleration
Y12 Physical Education AS90433
Newton’s Laws of Motion
Newton’s Third Law: Law of Action/Reaction
For every action there is an equal and opposite reaction
Y12 Physical Education AS90433
Force Summation
To give an object momentum eg throwing, kicking, hitting, the amount of momentum given to the object is determined by the ‘sum of all forces generated by each body part’.
Y12 Physical Education AS90433
Force Summation
Five Basic Guidelines to generate optimal force:Use of body segments Stretch outSequencing of Body segments – larger firstTiming of Body SegmentsFull Range of Motion
See Handout
Y12 Physical Education AS90433
Force Summation
Consider force summation in relation to drawing and driving.
Y12 Physical Education AS90433
Projectile Motion
Any object released into the air is a projectile. eg?
Six Factors Affect a Projectile’s PathGravityAir resistanceSpeed of ReleaseAngle of ReleaseHeight of ReleaseSpin
Y12 Physical Education AS90433
Projectile Motion
Of the six, the most important factors are Gravity which acts to decrease the height a projectile will travel and Air Resistance which acts to decrease distance.
Note a projectile will travel in a parabolic curve unless acted on by another influence
Y12 Physical Education AS90433
Gravity and Air ResistanceGravityEffects an object at a constant of 10NGravity is a weak attractive force but we
cannot escape it!
Air Resistance Effects the path of a projectile depending
on its mass, speed and/or surface area. Eg Graph the path of a petanque ball vs a shuttlecock
Y12 Physical Education AS90433
The greater the speed of release, the greater the distance traveled.
Two Parts:Initial Vertical SpeedInitial Horizontal SpeedThe greater the vertical speed: the higher and
longer (time) the projectile will fly.The greater the horizontal speed: the further it
will fly.
Speed of Release
Y12 Physical Education AS90433
Speed of Release
Force = Mass x Acceleration
To increase force can increase one or both. How?
This may create problems such as …
Remember Newton’s Second Law:
Y12 Physical Education AS90433
Angle of Release
You need an optimum angle to maximise the benefits of vertical and horizontal velocity.
If the angle is too high:
If the angle is too low:
Y12 Physical Education AS90433
Angle of Release•Angling of the release of the bowl allows for what to occur?
Y12 Physical Education AS90433
Height of Release
As the Height of Release increases, so does the distance that will be gained.
Not really relevant in bowls but definitely in Petanque – How?
Y12 Physical Education AS90433
Spin
In order to cause rotation a force has to be applied to one side of the COG.
Topspin Causes:
Backspin Causes:
Y12 Physical Education AS90433
Levers
Levers consist of 3 parts1. Resistance2. Effort3. Fulcrum or Pivot
1 2
3