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Intro to Biomechanics

An introduction to VCE Unit 1 Physical Education - biomechanics
by

mehdi bayani

on 24 October 2016

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Transcript of Intro to Biomechanics

Introduction to Biomechanics
The study of how living things move
Muttiah Muralitharan
Optoelectronic motion analysis
Ian thorpe
Multiple olympic gold winner
Mohammad Ali
How to throw the perfect punch
Quiz
Is mass and weight measuring the same thing?
Yes or No

What is the unit of measurement for mass
a) metres
b) kg
c) litres

How much newton of force does gravity make a 1 kilogram of mass exert.
a) 21N
b) 25N
c) 0N
d) 9.81N

Which of the following is the most appropriate definition of biomechanics?
A) the study of human movement
B) the study of biological organisms
C) the study of movement mechanics
D) the study of the mechanical aspects of biological organisms

Which of the following topics might be studied by biomechanists?
A) optimal form during the pole vault
B) forces on the spine during lifting
C) the mechanics of the jump shot
D) all of the above
An object at rest stays at rest and an object in motion stays in motion unless acted upon by an unbalanced force.
Summary
Newton's Second Law
Newtons third law of motion
Newtons Laws of Motion
Newton's First
Law of Motion
Newton's second law of motion explains how an object will change velocity if it is pushed or pulled.
Definition of velocity: the speed of an object in a given direction.
If you place a force on an object, it will accelerate...
This acceleration is directly proportional to the force
If you push twice as hard,
it will accelerate twice as much
This acceleration is directly proportional to the mass of the object.
If it is twice as heavy, it accelerates half as much
ACTIVITY
Write your own definition of Newton's Second Law of Motion
Force = mass x acceleration
Newtons = kg x m/s/s
QUESTION 1:
A Shot put weighing 4kg is thrown at an acceleration rate of 2m/s/s. What is the net force (in Newtons)?

QUESTION 2:
Determine the accelerations of a shot put which result when a 12-N net force is applied to the throw:
A) 3-kg object
B) 6-kg object.

QUESTION 3:
A net force of 15 N is exerted on an ball to cause it to accelerate at a rate of 5 m/s2. Determine the mass of the ball
f=m x a
a= f/m
m=f/a
For every action, there is an equal and opposite reaction.
Learning Outcome: L1
Students will understand how biomechanics relate to sports
Students will understand the terminologies involved in biomechanics
Scientific study of human movement
Move safely
Move effectively
Move efficiently
Better understanding of the human body and the various internal and external forces that affect movement.
Offers scientific knowledge that can improve performance
To improve sport techniques, equipment, and safety
To design and conduct programs to enhance individual movement skills (Adapted PE)
Reasons for Studying Biomechanics
Group
Group
Speed
Gravity
Force
Levers
Mass
Acceleration
Velocity
(cc) photo by theaucitron on Flickr
Basic terminologies in Biomechanics
velocity is the rate of change of position of an athlete (in m/s), which is the displacement divided by time.
Velocity = displacement/time= ____m/s
Acceleration = velocity/ time= ___m/s/s
acceleration is the rate of change of velocity of an athlete (in m/s/s), which is the change in velocity divided by time.
Amount of matter possessed by an object
Any action that changes or tends to change the motion of an object, measured in newton (N)
Force in biomechanics is usually exerted either by muscles acting on joints or by heavy external objects (like barbells or the ground) acting on the human body.
Natural force that pulls all objects toward the center of the earth
Speed = distance/time
Displacement
Displacement is the change in position of an object (in meters).
Biomechanics is the study of how living things move
It can assist in identifying safe movements, how to move effectively and efficiently
Newtons laws of motion
force = mass x acceleration
mass = force / acceleration
acceleration = force/ mass
Unit of measurement : force (N), acceleration (m/s/s) mass (kg)
three
Isometric force
Sub-maximal force
Isotonic force
two
one
Types of Force
Force without motion
Muscular contraction may or may not crate movement while applying a force. If the muscle length does not change, then isometric force is being applies.
write down 3 examples where this applies in a sport
Force with motion
An isotonic force is sufficient to change the state of motion of the object.
Provide 2 examples of isotonic force in sports
Force application must be optimal for successful performance.
ie. drop shot in badminton, trapping a soccer ball or putting in golf
Provide 2 examples where sub maximum force is being used in sports
Maximal force
Perfect timing, maximum muscle contraction and excellent technique is required to achieve maximum force
. when maximum force development is required the desired movement is usually the result of a combination of number of forces.
ie.
Speed & Velocity
Speed
Distance covered in a time frame determines the speed of an object
ie. 100m covered in 10 seconds = 10m per sec or 10 m/s
Usain Bolts world record time
100 meter in 9.58 sec =

200 meter in 19.19 sec=
Velocity
Speed of an object and a direction
How fast an object is traveling in a certain direction
Summary
There are 4 types of forces
Isometric Force
Isotonic Force
Submaximal Force
Maximum Force

Summation of force
The force of each different body segment is added to the final segment used to hit, release, or make contact, in a given sport, there-by maximising end force generated.

Distance covered in a time frame determines the speed of an object
Speed = distance / time

Velocity= Speed of an object and a direction
Force Summation
The force of each different body segment is added to the final segment used to hit, release, or make contact, in a given sport, there-by maximizing end force generated.
Many sports skills require force or speed to be maximized
For example, like in a shot put throw, the larger muscles (quadriceps) are required to flex the knee, then the energy is moved through to the gluts to extend the leg. Before energy is lost from a muscle group, the next largest comes, creating max force. The energy is then moved to the abdominal, the pectorals, then finally the biceps to give the shot put a powerful throw.
ie. A runners speed might be 10m/s. While the velocity will be 10 m/s in the direction he or she is traveling
Practical Questions
Provide an example of this process in 3 different movements
Types of Levers
First class levers
Second class levers
Class 3 levers
Levers
Will understand the types of levers
Will understand levers in sports
Will complete Activity 2 worksheet.
Levers have three main elements
What is it?
A simple machine consisting of a rigid bar pivoted on a fixed point and used to transmit force, as in raising or moving a weight at one end by pushing down on the other.
Levers are present in various objects such as scissors, wheelbarrows, bottle openers and even in the human body
1. a force arm (effort)
2. an axis, fulcrum or pivot point
3. a resistance arm (Load)
class 1 levers have the following characteristic:
the fulcrum is always between the force and the load
a longer force arm will favour the production of force, ie.
a longer resistance (load) arm will favour the production of speed ie.
class 2 levers have the following characteristic:
the resistance is always between the fulcrum and the force
the force and resistance (load) work in opposite direction
the longer force arm favours the production of force, at the expense of speed of movement
Class 2 levers are very rare in the human body
class 3 levers have the following characteristic:
The force/effort is always between the resistance (load) and the fulcrum.
the resistance arms is always longer than the force arm
the force and resistance (load) work in opposite directions
How does this relate to the human body?
The human body is made of many levers
your joints act as the fulcrum
your bones serves as the rigid bars of a lever
your muscles contract to produce force
the resistance can be any object you are carrying, pushing throwing of simply the weight of a body part
Motion
Linear Motion
Angular Motion
Three types of motion:
Linear motion
Angular motion
General motion
Linear motion occurs when a body moves along a straight line.

for example:
A ball thrown straight up and falling back straight down.

An athlete running 100m along a straight track

If a curved line is evident it is a curvilinear motion

ie. the flight path of a projectile is curvilinear ( such as a ball, javelin or long jumper)
Angular motion is evident when the body or an objects turns about an axis of rotation. It is defined as motion in a curved or circular path. Angular motion is an example of most human movement
examples of axis in the human body include:
shoulder joint
Elbow joint
The centre of gravity of a body
List as many angular motions in the body
General motion
General motion is a combination of both linear and angular.
it can be describes as the liner motion of the whole body that is achieved by the angular motion of some parts of the body.
In the 100 metre sprint the whole body moves in a straight line as a result of angular motion of the legs and arms
Motion is movement the body or object in space
Activity
Video
L3: Learning Outcome

-Students will understand Isometric and Isotonic movement and apply it to various sports
-Students will understand the summation of force
-Students will apply the knowledge to various sports
Type of Forces
Look at the list of sports below. Identify what type of forces is required to perform that task and explain why
a) Gold drive, trying to get maximum distance
b) soccer player heading the ball, trying to get the ball into the goal.
c) Tennis serve reaching 200 km/h
d) Swimmer jumping into the water
e) Long jump of 7 m
f) Drop shot in badminton
g) Holding a plank position to exercise your abdominal
h) Cricket player catching the ball
i) Volleyball player digging the ball
Complete Activity 2 Worksheet
Learning Outcome: L2

-Students will learn newtons Laws of motion
-Students will apply knowledge of the laws of motion by completing L2 activity sheet.

How it related to sports
Speed is the rate of change of position in an object (athlete).

It is expressed as distance moved (d) per unit of time(t).
Speed is measured in the same physical units of measurement as velocity, but does not contain an element of direction.

Example:
-The speed of long distance jogging for average persons is about 10 km/h.
-Athletic sprinters can run at 37 km/h within a short distance such as a 200 meters dash.
force= mxa = ___N
In sports list the many ways force is used to move and object/athlete?
L4: Levers
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