Transcript INTRODUCTION TO BIOMECHANICS FORCE

INTRODUCTION TO
BIOMECHANICS
What is Biomechanics?

The study of how the physical laws of
mechanics and physics apply to the
“Human Body”
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Why?
Improve performance
 Injury prevention and rehabilitation
 Design and development of more
efficient movements

Force Production
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Force is any push or pull activity that tends
to alter the state of motion of a body.
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The body could be a human body, ball,
discus, javelin, racquet, bat, etc
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The force can get the body to:
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Move
Speed it up
Slow it down
Stop
Change direction
Types of Forces
Force without motion – isometric force
 Force with motion – isotonic force
 Sub-maximal force
 Maximal force
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Force without Motion
Isometric force
 Isometric contraction
 Muscle length does not shorten


Eg: pushing against a wall, gripping a
cricket bat
Force with Motion
Isotonic force
 Isotonic contraction
 Muscle length shortens
 Changes the state of motion of the
object (body)
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Eg: shot put, taking a catch in cricket,
diving into a pool
Sub-maximal Force
Force needs to be at an optimal level
for successful performance
 Sometimes we want less than
maximum force
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Eg: tennis drop shot, chip in golf,
basketball lay-up
Maximal Force
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Some activities require maximal force
for a higher chance of success.
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This usually happens through
combination of a number of forces –
FORCE SUMMATION
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Eg: high jump, javelin, throw from the
outfield in softball, golf drive
Force Summation
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Combination of forces to produce a maximal
force
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2 types
 Simultaneously: explosive action of all body
parts occurs at the same time
• Eg: high jump take-off, vertical jump for
rebound in basketball
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Sequentially: body parts are moved in
sequence to generate a greatest force
• Eg: throwing, striking, kicking
Sequential Force Summation
http://www.youtube.com/watch?v=yCyvKk5-Mc
Sequential Force Summation
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To sequentially produce maximal force
effectively, the following principles need to be
applied:
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The summation of force is influenced by the:
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number of body parts used in the movement
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order and timing of their involvement
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way in which the body and body parts are balanced
Sequential Force Summation
Force Summation- Golf
-Read Handout
Velocity
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The speed of an object.
Velocity= Distance/Time
Directly related to the “Summation of
Forces”.
Momentum
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Momentum = Mass x Velocity
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So ten pin bowling ball and a tennis
ball are traveling at the same speed,
which has more momentum?
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Momentum can be transferred from
one object to another (Kinetic Energy)
Impulse
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Impulse is the time over which a force is
applied to an object Impulse changes the
motion of an object.
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Impulse = force (F) x time (t)
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Impulse is used by golf players to
increase the speed and distance the golf
ball travels eg follow through ‘v’
stabbing.
Golf Application
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Since most club heads weigh approximately the
same, the head's velocity at the impact point is
an important concept for hitting a golf ball long
distances. The faster the head is swung, the
greater the amount of kinetic energy—which is
proportional to the head's mass times its
velocity squared—that will be transferred from
the head to the ball. This energy transfer results
directly in a faster ball (acceleration) speed off
the golf tee.
Questions
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From you video, describe how your
“summation of force” is directly
affecting the “velocity” of your club
head and “momentum” transferred to
the golf ball.
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Also how would a big bend in your
front arm affect force summation?