Biomechanics
Biomechanics
The study of forces and their effects on the human body
Sir Isaac Newton developed three basic laws that explain the relationship between motion and force
A push, a pull or a twist
Force = Mass x Acceleration
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
Inertia is… a body’s 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?
This soccer ball will remain at rest until a force acts on it…e.g. strong winds, or someone kicking it
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…
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
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, theground will exert an equal and opposite force on the person, pushing them up
into the air Upward
Downward
HANDBALL EXAMPLE In your groups, choose ONE of Newton’s
LawsDescribe how you can use this law to your
advantage in Handball
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
FORCE ARM
Resistance
Fulcrum
FORCE
Resistance ARM
Allow force to be applied from Outside the body
e.g.
Are inside the human body. Most important Levers These levers are made up of a:
Joint = FulcrumBones = Lever armsMuscles = Force
Load = resistance Effort = force
Levers can be classed into 3 types:
1st Class 2nd Class 3rd Class – Most levers in human body are 3rd
class
In a 1st Class Lever, the Fulcrum sits between the load (resistance) and force applied (effort)
e.g. See-saw
In a 2nd Class Lever, the Load (resistance) sits between the fulcrum and the force applied.
e.g. Wheel Barrow
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
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.
1. What class of lever are most of the limbs in human body?
2. Force = _______ x ________ 3. Newton’s 1st law is the law of _______ 4. Newton’s 2nd law of reaction means… ? 5. What type of joint is the elbow joint? And
what muscle causes elbow flexion
1. What class of lever are most of the limbs in human body? 3rd CLASS
2. Force = MASS x ACCELERATION 3. Newton’s 1st law is the law of INERTIA 4. Give an example of Newton’s 2nd law? BOUNCING A BALL, JUMPING 5. What type of joint is the elbow joint? And
what muscle causes elbow flexion HINGE JOINT, BICEP
‘the sum of all forces generated by each body part’
Force summation allows maximum force to be produced
For maximum force production:1. The force from all different body segments
needs to be added together2. Use large muscles then smaller muscles3. You need to sequence timing of body
segments4. The more body segments that are involved in
the movement, the more possible force that can be produced
Throwing example:
Time
Large Force
Small ForceShoulder/arm
Shoulder/arm
Hand
Hand
Trunk
Hip/thigh/leg
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
A projectiles speed of release is determined by: Force summation Levers
The greater the speed of release = the greater distance traveled.
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
By increasing the height of release, the object will travel a greater distance
e.g.
Complete the revision worksheet