Year 12 Physical Education

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Year 12 Physical Education

• Biomechanics

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What is biomechanics?

• The study of forces and their effects on the
  human body

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Newtons Laws of motion

• Sir Isaac Newton developed three basic laws that
  explain the relationship between motion and force

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What is a force?

• A push, a pull or a twist
• Force Mass x Acceleration

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Newtons 1st Law

• LAW OF INERTIA
• A body continues in its state of rest or uniform
  motion unless an unbalanced force acts upon it
• So what does this mean?
• A body will remain at rest or will continue
  moving (in the same direction) until another
  force acts on it

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• Inertia is
• a bodys tendency to remain at rest or in motion.
  The more mass an object has, the larger its
  inertia is. Therefore is more reluctant to
  change its state of motion.
• Who has more inertia
• in this image?

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Newtons 1st Law - Example

• This soccer ball will remain at rest until a
  force acts on it
• e.g. strong winds, or someone kicking it

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Newtons 2nd Law

• LAW OF ACCELERATION
• The acceleration of an object is directly
  proportional to the force causing it, is in the
  same direction as the force, and is inversely
  proportional to the mass of the object
• This means
• When a force is applied to an object it will move
  in the direction the force was applied, and,
  depending on the size of the force and the size
  of the object, the object will accelerate
  accordingly
• Class experiment

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Newtons 2nd Law

• A smaller object will move faster than a larger
  object.
• A greater force will move an object faster than a
  smaller force

Force Mass x acceleration
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Newtons 3rd Law

• THE LAW OF REACTION
• Whenever a force is applied there is an equal
  and opposite reaction
• e.g. Jumping
• If a person exerts a force onto
• the ground in order to push off, the
• ground will exert an equal and opposite
• force on the person, pushing them up
• into the air

Downward
Upward
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Newtons Laws

• HANDBALL EXAMPLE
• In your groups, choose ONE of Newtons Laws
• Describe how you can use this law to your
  advantage in Handball

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Levers

• Levers allow you to apply force and speed more
  easily.
• Consist of 5 parts - Fulcrum (pivot point),
  Force, Force arm, Resistance and a Resistance Arm

Resistance
FORCE
Fulcrum
FORCE ARM
Resistance ARM
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External Levers

• Allow force to be applied from Outside the body
• e.g.

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Internal Levers

• Are inside the human body.
• Most important Levers
• These levers are made up of a
• Joint Fulcrum
• Bones Lever arms
• Muscles Force
• Load resistance
• Effort force

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Classification of Levers

• Levers can be classed into 3 types
• 1st Class
• 2nd Class
• 3rd Class Most levers in human body are 3rd
  class

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1st Class

• In a 1st Class Lever, the Fulcrum sits between
  the load (resistance) and force applied (effort)
• e.g. See-saw

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2nd Class

• In a 2nd Class Lever, the Load (resistance) sits
  between the fulcrum and the force applied.
• e.g. Wheel Barrow

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3rd Class

• In a 3rd class lever, the force applied sits
  between the Fulcrum and the load (resistance)
• Third class levers allow more speed to be
  produced because resistance arm is longer than
  force arm
• e.g. Bicep curl

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Long vs. Short Levers

• To Manipulate the Lever length the resistance arm
  needs to be altered (via bending or straightening
  the joint)
• Longer levers result in greater speed at the end
  of the lever arms this is beneficial for
  throwing and striking objects (e.g. throwing a
  handball).
• Short levers result in fast and strong movements
  to occur this is beneficial for moving body
  parts quickly and applying strength for pushing,
  pulling and lifting objects.

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5 Quick Questions

• 1. What class of lever are most of the limbs in
  human body?
• 2. Force _______ x ________
• 3. Newtons 1st law is the law of _______
• 4. Newtons 2nd law of reaction means ?
• 5. What type of joint is the elbow joint? And
  what muscle causes elbow flexion

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5 Quick Questions - ANswers

• 1. What class of lever are most of the limbs in
  human body? 3rd CLASS
• 2. Force MASS x ACCELERATION
• 3. Newtons 1st law is the law of INERTIA
• 4. Give an example of Newtons 2nd law?
• BOUNCING A BALL, JUMPING
• 5. What type of joint is the elbow joint? And
  what muscle causes elbow flexion
• HINGE JOINT, BICEP

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Force summation

• the sum of all forces generated by each body
  part
• Force summation allows maximum force to be
  produced
• For maximum force production
• The force from all different body segments needs
  to be added together
• Use large muscles ? then smaller muscles
• You need to sequence timing of body segments
• The more body segments that are involved in the
  movement, the more possible force that can be
  produced

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Force summation

• Throwing example

Large Force
Hand
Force Produced
Small Force
Shoulder/arm
Hand
Trunk
Shoulder/arm
Hip/thigh/leg
Time
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Force Summation Cont
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Projectile Motion

• As soon as an object is thrown it becomes a
  projectile.
• The distance an object travels is dependant on
  many factors, including
• Speed of release
• Angle of release
• Height of release

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Speed of release

• A projectiles speed of release is determined by
• Force summation
• Levers
• The greater the speed of release the greater
  distance traveled.

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Angle of release

• When aiming for maximum distance, the optimal
  angle of release is 45 degrees
• Different activities require a different angle of
  release
• e.g. Hand ball shot at goal (-45 degrees)
• e.g. Throwing a shot put (45 degrees)
• High release to get greater distance

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height of release

• By increasing the height of release, the object
  will travel a greater distance
• e.g.

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Anatomy Worksheet

• Complete the revision worksheet