Download Bio-physical principles

Bio-physical principles
Apply to your skill
3 parameters that affect projectile
motion
• Angle of release (and air resistance)
– Determines SHAPE of trajectory
– Parabolic trajectory neglecting air resistance
• Speed of release
– Determines size of projectile’s trajectory
– Combination of ANGLE and SPEED determine the
projectile’s RANGE
• Projection height
– Difference between height at release and height on
landing
– Increased projection height = increased flight time
FUNCTIONS OF LEVERS
All levers have 2 functions:
•
They either:
1. Increase the speed at which an object can move
with a given effort.
E.g. driver as opposed to an iron in golf
2. Increase the resistance that can be moved with a
given effort
E.g. Bench press – wide arms more force
Force summation
To gain maximumpower, the force needs to be
generated by:
Using as many body parts as possible.
In the correct sequence (use large muscles
first & then the smallest muscles last but
fastest).
With the correct timing.
Though the greatest range of motion.
Balance & Stability
Line of Gravity
Is the vertical line that passes through the
centre of gravity to the ground
Centre of gravity
Line of gravity
Base of support
Base of support
Is the area within an object’s point of
contact with the ground. The larger the
area the base of support covers, the more
stable an object will be.
Base of support
Base of support
Principles of Balance
Balance is a desirable attribute in the performance of
many skills. A body is most stable when the principles of
balance are applied
1. Anything can be balanced if its centre of gravity is directly
over its base of support
2. The wider the base of support the more balanced or
stable the object or body is.
3. The lower the centre of gravity the more balanced or
stable the object is.
4. As one body part moves another must move to
compensate that movement
Mechanical Principle: Motion
• Newton’s First Law
–
Law of inertia
• Newton’s Second Law
–
Law of Acceleration
• Newton’s Third Law
–
Law of Action and Reaction
Newton’s 1st law of motion
(law of inertia)
A body will maintain a state of rest or constant
velocity unless acted on by an external force.
Implication: -Tackling in Rugby
-Deflection of the ball in basketball
-Weight training
The inertia of an object is directly proportional to
its mass. Therefore you need more force to alter
the movement of a heavier object
Newtons 2nd law of motion
(law of acceleration)
A force applied to a body causes an acceleration of
that body of a magnitude proportional to the
force, in the direction of the force, and inversely
proportional to the body’s mass.
OR
F = ma (extremely important!!!)
Implication: Apply forces in direction of desired
movement.
-Kicking a soccer ball
-tackling in rugby (again!)
-Sprinting
-Almost everything in life
Newtons 3rd law of motion
(law of reaction)
For every action, there is an equal and opposite
reaction
Implication: Use reaction forces to your advantage
• Ground reaction forces in running
• Gravitational forces in weight training
• Catching a ball, forces of hands must be able to
resist force of ball
• Swimming
Mechanical Principle: Leverage
• Lever - mechanical device used to produce a
turning motion around a fixed point called an
axis.
• Lever components
–
–
–
Fulcrum - center or axis of rotation
Force arm - distance from the fulcrum to the point of
application of the force
Resistance arm - distance from the fulcrum to the weight
on which the force is acting