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=**Welcome to the Year 12 Human Movement Wiki**! =


 * __12SH__**

Tess Attenborough Stewart Boyd Melynda Bungbrakearti Bridget Chivers Renee Cunich Anna Flanagan Michael Gosman Asher groves Josh Heuer Rachel McDonald Alex Page Ben Ruane Jess Spence Hannah Tracey

**__12EP__**
Myles Balthazaar Ellen Bruce Ellie Crossman Tom Daniels Annie Gould Thomas Hawketts Kristie Hoop Daniel Jordinson Georgia Nelson-Tyers Serena Shaw Rose Spyropoulos Morgan Wallace

=**__BIOMECHANICS__** =

 For your selected topic you need to provide a **summary** (you may include pictures, diagrams etc) as well as some **revision questions**. You may then provide a link to either a word document with the answers to these questions, or a link to a website where students will be able to find the answers.

Make sure you reference any sources you get your information from.

=**TOPICS:**=

__VELOCITY__ //- (Jess Spence)//

 * SUMMARY:**


 * REVISION QUESTIONS:**

**__ACCELERATION__ //- (Rosy Spyropoulos)//**
> > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > As a word "acceleration" refers to the act of accelerating or the process by which one accelerates. In Physics however, acceleration refers to the rate of change in velocity of an object in relation to time. As a simple way to understand acceleration consider the formula of acceleration, where it is nothing but the final speed less the original speed divided by time. Speed is different from acceleration and is calculated based on what distance has been covered divided by the time taken. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > REVISION QUESTIONS:
 * SUMMARY:**
 * Definition Of Acceleration:**
 * An increase in rate of change; "modern science caused an acceleration of cultural change"
 * The act of accelerating; increasing the speed
 * (in terms of physics) a rate of increase of velocity

**__TORQUE__ //- (Michael Gosman)//**
//Torque // is a measure of how much a force acting on an object causes that object to rotate.  The object rotates about an axis, which we will call the pivot point. Torque is rotational force or the ability to overcome resistance to rotation. It is the cross product of force and radius. Torque is the amount of force applied tangentially to a circle.  Torque is used to create tension (tension is power by creating a straight pull – but differs from torque) Twisting the lid of a jam jar, to remove or replace the lid, is an example of applying torque. If the lid refuses to budge, the torque applied is called static torque. Static torque is torque applied to a non-accelerating object. Therefore, using a force to rotate the jar lid at a constant angular speed is also called static torque. When the jar lid first begins to move, it is accelerating from a stationary state. Torque applied to an object with angular acceleration is called dynamic torque. The amount of torque developed is proportional to the force applied and to how far from the centre of the rotation the force is applied. Pushing a door harder applies more torque to the door. Pushing a door near its hinges may not open the door; pushing with the same force on the door farther away from the hinged side may open the door.
 * SUMMARY:**


 * REVISION QUESTIONS:**

1) What is Torque? 2) What is Torque used to create? 3) Use an example of a everyday activity that that involves Torque?

**__IMPULSE__ //- (Rachel McDonald)//**

 * SUMMARY:**
 * REVISION QUESTIONS:**

**__MASS__ //- (Annie Gould)//**
matter
 * SUMMARY:**
 * REVISION QUESTIONS:**
 * 1) Explain at least one main difference between mass and weight.
 * 2) If an object on Earth weighs 34 kg, what is it’s mass?
 * 3) Why would a small, water balloon fall faster than a large, air-filled balloon?
 * 4) If an objects weight on Earth is 10kg, but on Jupiter its weight is 23.6kg; what is its mass on Earth and on Jupiter?

**__EQUILIBRIUM__ //- (Josh Heuer)//**

 * SUMMARY:**
 * 1. || a state of rest or balance due to the equal action of opposing forces. ||


 * 2. || equal balance between any powers, influences, etc.; equality of effect. ||
 * equilibrium**
 * 1) What causes and object to enter a state of euilibrium?
 * 2) What causes an object to exit a state of euilibrium?
 * 3) Give 3 examples of a state of equilibrium in 3 different sports?

**__INERTIA__ //- (Ellie Crossman)//**

 * SUMMARY:**
 * REVISION QUESTIONS:**

**__MOMENTUM__ //- (Georgia Nelson-Tyers)//**

 * SUMMARY:**
 * Momentum is described as the measure of motion, being equal to that of an object's mass and velocity. Momentum can only be produced if the object is moving. When there is an increase in momentum then there is an increase in the amount of distance being travelled by the object. This can also be effected by the level of impulse at the beginning and during the motion, which is described as the momentum/impulse relationship. In order for an object to travel in a straight linear motion or on a flat surface and increase momentum, the force that HAS acted on the object or IS acting on the object needs to be strong enough to overcome the mass of the object. If the object is moving on a surface that is at an angle such as up-hill or down-hill then the amount of force needed to continue motion and momentum will change. This can be influenced by factors such as air resistance, gravity, friction and gradient. Momentum will continue until the force is not strong enough to overcome the mass of the object or until an external or internal force acts on the object in order to stop it. Momentum can also be transferred from an object onto an other, however the amount of velocity and momentum which is transferred relies heavily on the mass of the object. It can also depend on the level of momentum of the first object and whether that is strong enough to overcome the mass of the second object. **
 * Pushing an empty box across a flat surface such as a table will not require much force, however the impulse will need to remain constant or the box will not move. If a person was trying to move this box up-hill then more constant force would be needed to move the box and create momentum, or if the box was moving down-hill then less constant force would be needed to move the box as gravity would act as a force that would create momentum along with the type of surface.**
 * //Revision Questions:// **
 * // 1. What change would air resistance have on the level of momentum being produced by the object if it was traveling in a pure linear motion on a flat surface? What other factors may effect the level of change? // **
 * 2. Give some examples of sports that involve the transference of momentum between objects. **
 * 3. What is one key factor in the transference of velocity and momentum from one object onto another? **
 * REVISION QUESTIONS:**

**__FRICTION__ //- (Serena Shaw)//**

 * SUMMARY:**
 * REVISION QUESTIONS:**

**__FORCE__ //- (Hannah Tracey)//**
Force is a pushing or pulling which changes a body's state of motion; whether it changes its speed, direction or enables it to begin movement. This body may be a human or an object such as a bat or a ball. These forces are mostly external. Internal forces usually occur in human bodies. The **equation** to determine force is: F=m.a F: Force (Newtons) m: Mass (kilograms) a: Acceleration (metres per second squared) **Types of Forces** //__Isometric Force:__ // This type of force does not involve movement or motion. It occurs when a contraction is applied. For example, if a person is gripping a bat or pushing against a wall, their muscles contract. However, the length of these muscles do not change. Static stretching may include isometric forces, as muscles are stretched to their farthest point, then the contraction is maintained and held in that position. When holding this position, the muscle length does not change, therefore an isometric force is applied. //__Isotonic Force:__ // This type of force, unlike isometric force, does involve movement or motion of an object or body. For example, when throwing a ball, muscles are contracted and change length. Other examples include hitting a ball or pushing off at the beginning of a sprint. //__Sub-maximal Force:__ // This occurs when the application of force is graduated, or below maximum effort. A limited number of muscle motor units are used. For example, when putting in golf, not all muscles in the body are used. Muscles that may be used include those in the arms, and perhaps those in the abdominal region and the upper legs. Another example of when sub-maximal force is used is when a lay-up is performed in basketball. //__Maximal Force/Force Summation:__ //  This type of force requires maximum muscle contraction. For example, if a ball is thrown or kicked for distance, a maximum effort of the body is used as a great amount of force is required. Force summation may be achieved either //simultaneously //or //<span style="font-family: "Arial","sans-serif";">sequentially. // <span style="font-family: 'Arial','sans-serif'; font-size: 10pt;"> Simultaneous Force Summation <span style="font-family: "Arial","sans-serif"; font-size: 10pt;"> This occurs when all body parts contract at the same time when an explosive effort is needed. An example may be a take-off in high jump, when a maximum effort is needed in order to reach the height needed. <span style="font-family: "Arial","sans-serif"; font-size: 10pt;"> //<span style="font-family: "Arial","sans-serif";">Sequential Force Summation // <span style="font-family: "Arial","sans-serif"; font-size: 10pt;"> This occurs when body parts move in a sequence. It requires using as many body parts as possible, using the largest body parts and muscle groups first. This type of force also requires sequentially accelerating each body part so its momentum passes on to the next body part. This also enables each body part to be stabilised so the next accelerates around the stable base. An example of sequential force summation includes kicking for distance, where different muscles are used in an order, working together to create a maximum effort. Another example includes a long golf drive. (http://blog.swingtraining.net/2007/12/12/when-does-bat-speed-happen.aspx) <span style="font-family: "Arial","sans-serif"; font-size: 10pt;">1. If an object weighs 15kg and accelerates at a speed of 2.5m/second squared, determine the force applied. <span style="font-family: "Arial","sans-serif"; font-size: 10pt;"> 2. Determine the difference between isotonic and isometric forces, and name an example of each. <span style="font-family: "Arial","sans-serif"; font-size: 10pt;"> 3. Describe how throwing a ball for distance uses a sequential force summation, using the diagram above.
 * SUMMARY:**
 * REVISION QUESTIONS:**

**__INTERNAL FORCE__**

 * SUMMARY:**
 * REVISION QUESTIONS:**

**__EXTERNAL FORCE__**

 * SUMMARY:**
 * REVISION QUESTIONS:**

**__FORCE SUMMATION__**

 * SUMMARY:**
 * REVISION QUESTIONS:**

**__CENTRE OF GRAVITY__ //- (Elise O'Dea)//**
A persons’ centre of gravity (COG) is defined as ‘The point around which a body’s mass is equally balanced in all directions – The total mass of the object is concentrated at this point’ ([|www.science.org.au]). Generally, an adult males’ COG is found to be 2.5cm bellow their navel, or 57% of their height measured from the ground whereas in most adult females case, their COG is 55% of their height from the ground. 1. Does the centre of gravity change depending on body position?
 * SUMMARY:**
 * REVISION QUESTIONS:**

**__GRAVITY__ //- (Daniel Jordison)//**

 * Gravity is the force of attraction of all masses on the surface of the earth to the centre of the earth.
 * The equation for the force of gravity is F = mg.


 * The major result of this force is that all objects fall at the same rate, regardless of their mass.
 * Whilst a body is in the air it is subject to a downward acceleration, due to gravity, of approximately 9.81m/s²
 * In Biomechanics, Gravity is related to centre of gravity, balance and stability, equilibrium etc..


 * What is the gravity equation?
 * What is the most outstanding characteristic of gravity?

**__PROJECTILE__ //- (Morgan Wallace)//**
[|trajectory]
 * SUMMARY:**
 * A projectile**
 * Gravity-**
 * Air Resistance**
 * Drag Force- (**
 * Frictional Force-**
 * Propelling Force**
 * 1) Name the three factors affecting any projectile
 * 2) What is a projectile? What is it's flight path called?
 * 3) Give 4 examples of sport where projectiles are used. Estimate the aprox. optimum angle for each sport.
 * 4) Two objects are thrown. given they have the same amount of propelling force and angle release, which one will travel furthest. the 5 kg ball or teh 10 kg ball.

**__TRAJECTORY__- //(Anna Flanagan)//**

 * SUMMARY:**
 * A trajectory is the path a moving object, such as a projectile or satellite, follows through space. A trajectory can be described mathematically either by the geometry of the path, or as the position of the object over time. **

The trajectory varies with the weight and shape of the projectile, with its initial velocity, and the angle at which it is fired. The general shape of a trajectory is a parabola. Factors effecting the trajectory of a projectile are shown in the diagram below:

References: http://qanda.encyclopedia.com/question/trajectory-80833.html http://en.wikipedia.org/wiki/Trajectory http://hyperphysics.phy-astr.gsu.edu/Hbase/traj.html **__ANGLE OF PROJECTION__ //- (Alex Page)//**

 
 * SUMMARY:**

**__AIR RESISTANCE__ //- (Melynda Bungbrakearti)//**
The friction from air molecules hitting an object as the object moves through the air, it’s a contact force that opposes the motion of objects moving in the air. The more air molecules an object collides with, the greater the air resistance. Objects will accelerate till the air resistance force increases enough to balance the downward force of gravity. __Two most common factors affecting air resistance:__ <span style="font-family: Arial,sans-serif; font-size: 10pt;">__Other factors affecting air resistance:__
 * SUMMARY:**
 * <span style="font-family: "Arial","sans-serif"; font-size: 10pt; mso-ansi-language: EN-AU;">Speed of the object – An increase of speed leads to an increase of air resistance as an increase of speed leads to an increase of drag, hence air resistance.
 * <span style="font-family: "Arial","sans-serif"; font-size: 10pt; mso-ansi-language: EN-AU;">The surface area of the object – Increased surface area leads to an increase of air resistance due to a larger force of gravity acting upon the larger object.
 * <span style="font-family: "Arial","sans-serif"; font-size: 10pt; mso-ansi-language: EN-AU;">Nature of the surface area (smooth or rough)
 * <span style="font-family: "Arial","sans-serif"; font-size: 10pt; mso-ansi-language: EN-AU;">The projectile’s shape
 * <span style="font-family: "Arial","sans-serif"; font-size: 10pt; mso-ansi-language: EN-AU;">The projectile’s velocity
 * <span style="font-family: "Arial","sans-serif"; font-size: 10pt; mso-ansi-language: EN-AU;">The projectiles mass or weight
 * <span style="font-family: "Arial","sans-serif"; font-size: 10pt; mso-ansi-language: EN-AU;">The spin out upon the object
 * <span style="font-family: "Arial","sans-serif"; font-size: 10pt; mso-ansi-language: EN-AU;">The projectiles momentum

<span style="font-family: "Arial","sans-serif"; font-size: 10pt; mso-ansi-language: EN-AU;"> A ball kicked at 45 <span style="font-family: Symbol; font-size: 10pt; mso-ansi-language: EN-AU; mso-ascii-font-family: Arial; mso-bidi-font-family: Arial; mso-char-type: symbol; mso-hansi-font-family: Arial; mso-symbol-font-family: Symbol; msoansilanguage: EN-AU; msoasciifontfamily: Arial; msobidifontfamily: Arial; msochartype: symbol; msohansifontfamily: Arial; msosymbolfontfamily: Symbol;">° <span style="font-family: "Arial","sans-serif"; font-size: 10pt; mso-ansi-language: EN-AU;"> at 35 metres per second, would reach a maximum range of 125 metres had air resistance had no affect on it. In reality, the ball will only reach a range of 65 metres due to the force of air resistance acting upon it. <span style="font-family: "Arial","sans-serif"; font-size: 10pt; mso-ansi-language: EN-AU;"> When a ball is kicked or thrown, the air around it acts in two ways: <span style="font-family: "Arial","sans-serif"; font-size: 10pt; mso-ansi-language: EN-AU;">Equipment and clothing in sport has been designed to increase the amount of air resistance. <span style="font-family: "Arial","sans-serif"; font-size: 10pt; mso-ansi-language: EN-AU;"> E.g Lycra body suits for athletes and specially designed helmets for cyclists. <span style="font-family: "Arial","sans-serif"; font-size: 10pt; mso-ansi-language: EN-AU;"> __References:__
 * 1) <span style="font-family: "Arial","sans-serif"; font-size: 10pt; mso-ansi-language: EN-AU;">Frictional force through which the projectile must push
 * 2) <span style="font-family: "Arial","sans-serif"; font-size: 10pt; mso-ansi-language: EN-AU;">Drag force from which the object must escape
 * <span style="font-family: "Arial","sans-serif"; font-size: 10pt; mso-ansi-language: EN-AU;">[]
 * <span style="font-family: "Arial","sans-serif"; font-size: 10pt; mso-ansi-language: EN-AU;">[]
 * <span style="font-family: "Arial","sans-serif"; font-size: 10pt; mso-ansi-language: EN-AU;">[]

__**MAGNUS EFFECT**__ **//- (Tom Daniels)//**

 
 * SUMMARY:**

**__REBOUND AND SPIN__ //- (Ben Ruane)//**
 
 * SUMMARY:**

**__CO-EFFICIENT OF RESTITUITION__ //- (Renee Cunich)//**
 
 * SUMMARY:**

**__LINEAR MOTION__ //- (Myles Balthazaar)//**
 
 * SUMMARY:**

**__ANGULAR MOTION__ //- (Ellen Bruce)//**
Angular motion is the application of an **eccentric force** which creates rotation about an axis – either vertical or horizontal. **Eccentric Force** = any force applied away from the centre of gravity All of Newton’s laws apply **Moment of Inertia** = resistance to change in rotation. It depends on mass and how the weight is distributed from the axis of rotation. If the mass is further away then the moment of inertia will be greater **Conservation of Angular Momentum** = no angular momentum is lost, it is only transferred from/to another body. It explain the sequential summation of force **Angular displacement** = change in angular position of an object. Measured by degrees, radians or revolutions Measured by degrees/second. = displacement ÷ time How quickly velocity changes Measured by degrees/second/second = Velocity ÷ time = displacement ÷(time)2
 * SUMMARY:**
 * Angular Velocity ** = rate of change of angular displacement or how quickly an object rotates.
 * Angular Acceleration = ** rate of change of angular velocity.

1.Give 4 sporting activities which involve an angular force 2.What axis is rotation about in diving 3.What axis is rotated abut in figure skating 4.What is moment of inertia
 * REVISION QUESTIONS **

 

**__CURVILINEAR MOTION__**
 
 * SUMMARY:**

**__CLASSES OF LEVERS__ //- (Tess Attenborough)//**
 A lever is a simple machine used to amplify a small force into a larger one. It is usually a rigid object which turns about a fixed point. Levers can be used internally (eg bones) and externally (eg racquets). All levers have a force arm, a resistance arm and an axis (also known as the fulcrum or turning point). There are three classes of levers, in which the positions of the fulcrum, effort and load vary. [] First class levers can be used to generate great strength or speed. These two things can be achieved by moving the axis. The closer the axis to the resistance or load (and therefore the longer the force arm), the greater the strength generated can be. If the axis is moved further from the resistance (and the resistance arm is lengthened), greater speed can be generated. [] Second class levers amplify strength that humans apply to objects. In this class of levers, the resistance is always between the axis and the effort applied. [] Within the body, the levers are mostly third class. They have a long resistance arm and a short force arm, and the force is applied between the resistance and the axis. These levers generate great speed.
 * SUMMARY:**


 * __Revision Questions__**
 * 1) What are 3 examples of first class levers?
 * 2) What is another word for fulcrum?
 * 3) What kind of lever do you utilise while kicking a ball?
 * 4) What are two examples of second class levers?
 * 5) What is the purpose of a lever?
 * 6) What are the three main elements of all levers?
 * 7) Can you draw each of the three classes of levers?