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Force Production Force is any push or pull activity that tends to alter the state of motion of a body. The body could be a human body, ball, discus, javelin, racquet, bat, etc The force can get the body to: Move Speed it up Slow it down Stop Change direction
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INTRODUCTION TO BIOMECHANICS
What is Biomechanics?
The study of how the physical laws of mechanics and physics apply to the “Human Body”
Why?Improve performanceInjury prevention and rehabilitationDesign and development of more
efficient movements
Force Production Force is any push or pull activity that tends to
alter the state of motion of a body.
The body could be a human body, ball, discus, javelin, racquet, bat, etc
The force can get the body to: 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
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)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 forceEg: tennis drop shot, chip in golf,
basketball lay-up
Maximal Force
Some activities require maximal force for a higher chance of success.
This usually happens through combination of a number of forces – FORCE SUMMATION
Eg: high jump, javelin, throw from the outfield in softball, golf drive
Force Summation Combination of forces to produce a maximal force
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
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=yCyv-Kk5-Mc
Sequential Force Summation
To sequentially produce maximal force effectively, the following principles need to be applied:
The summation of force is influenced by the: number of body parts used in the movement order and timing of their involvement way in which the body and body parts are
balanced
Sequential Force Summation
Force Summation- Golf
-Read Handout
Velocity
The speed of an object.
Velocity= Distance/Time
Directly related to the “Summation of Forces”.
Momentum
Momentum = Mass x Velocity
So ten pin bowling ball and a tennis ball are traveling at the same speed, which has more momentum?
Momentum can be transferred from one object to another (Kinetic Energy)
Impulse
Impulse is the time over which a force is applied to an object Impulse changes the motion of an object.
Impulse = force (F) x time (t)
Impulse is used by golf players to increase the speed and distance the golf ball travels eg follow through ‘v’ stabbing.
Golf Application
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
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.
Also how would a big bend in your front arm affect force summation?