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ATAR Physical Education yr 11 > Biomechanics > Flashcards

Flashcards in Biomechanics Deck (22)
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define linear motion

Linear motion simply means motion in a straight line, there is no rotation and all body parts move in the same direction at the same speed


name an example of linear motion

a badminton drives it goes in a straight line
E.g. An ice skater gliding after they completed a movement or a cyclist who stops pedaling (straight line motion)


define speed velocity and and acceleration and how they relate to linear motion

speed: the rate at which someone or something moves or operates or is able to move or operate
velocity: is a vector (meaning it is measured in magnitude and direction) a definition for velocity is that it is speed with direction. instantaneous velocity is known is the average velocity the formula for velocity is displacement over the time taken. Velocity is measured in distance over time.
acceleration: The rate in which the velocity changes in a certain amount of time the formula for acceleration is change in velocity over the amount of time. Acceleration is measured in meters per second^2. the opposite of acceleration is deceleration foe example at a certain period when the shuttle cock is about to hit the ground and it is decelerating the shuttle cock may be flying at 0.6 meters per second^2


what is angular motion

motion on a rotational axis


what is newtons fists law

a body will continue in its state or uniform in motion unless acted on by another force


what is newtons second law and the formula

F= mxa
if you want too hit a object with higher acceleration you must hit it with more force as the object has constant mass
the large forces must be absorbed by the body for example when you catch a netball therefor it is important that the force is absorbed in the most appropriate way for example flexing at the knee when catching a netball


what is newtons 3rd law

that every action has an equal and opposite reaction for example when jumping to catch a netball the foot push against the ground this will mean the ground will push back with an equal and opposite force


what is general motion and an example

general motion is is linear and angular motion combined an example off this is a kick in soccer the run up is linear motion and the trunk rotation is linear velocity and the rotation of the thigh and the leg is angular motion


what is simultaneous movement and when is it used

often in accuracy based sports all the movements off the body will occur at the same time an example of this is a netball shot


what is sequential movement and what is it used for

sequential movement the movements will summate and will go one after each other the just before one body part deaccelerates the next body part will move this is summation of forces and will insure maximum velocity and distance


how does summation of forces occur

simultaneously and sequentially the forces will summate to achieve either accuracy of maximum velocity

1 the stronger and the larger muscles will move first and then the slower faster muscles
2 sequentially moving moving each body part to achieve optimum momentum
3 using as many body parts as possible so more forces is applied
4 one segment will move just before the presiding limb deaccelerates


what is projectile motion

A projectile is an object propelled into the air or water and affected only by the forces of gravity and air resistance


why is timing important when summating forces

because each body part should be increasing the velocity and the momentum should be transferd to the next body part as the time goes and if the body parts move too early or too late maximum velocity will not be obtained


explain air resistance and gravity

Air resistance
Without air resistance, a projectiles horizontal velocity would remain constant
Important in sports like discus, javelin, golf where air resistance affects the aerodynamic characteristics of the projectile

Downwards force which brings projectiles back to the ground (“what comes up, must come down”)
Causes objects to accelerate towards the earth at a rate of 9.81m/s2 and is responsible for giving projectiles their parabolic flight path – without gravity a projectile keeps going forever!


what is a trajectory

The path of a projectile is referred to as its trajectory


how do Angle of release, Speed of release, Height of release effect the projectile motion

The angle of release of a projectile determines trajectory shape. With all other things held constant it also determines. The time the object stays in the air
The horizontal distance the object moves

height of release
Many sports involve releasing a projectile from a given height then landing at ground level.
The greater the height of release of a projectile, the greater the horizontal distance it will cover, provided all other factors are equal.

The greater the speed or velocity of release, the greater the distance a projectile will carry.
The speed of release is the most important factor when maximising the distance travelled.


examples of static balance

The ability to hold a stationary position
Completing a handstand
Swimmer/runner on the blocks at the start of a race
Pyramid in cheer leading


explain dynamic balance

The ability to hold a moving position to execute an outcome
Catching a wave whilst surfing
Riding a skateboard
Kicking a ball in soccer
Player continuing to move after being hit in a tackle by an opposing player


explain what the the center of gravity is

The theoretical point in an object, located either inside or outside of the body, where all of the body’s mass is equally distributed.
Standing still – centre of gravity is located in the abdominal cavity, about 6 inches above the pubis symphysis
As your position changes – so does your centre of gravity
The position of the centre of gravity will determine whether the body is in balance


explain what the line of gravity is

The Line of Gravity is an imaginary vertical line passing downwards through the centre of gravity to the ground or surface the person is on.
The closer the line of gravity is to the limits of the base of support, the less the degree of stability of the object
Movement is easier when the line of gravity falls outside the object’s base of support


explain what a base of support is

Area bound by the outermost regions of contact between a body and support surface.
It refers to the area beneath an object or person that includes every point of contact that the object or person makes with the supporting surface.
These points of contact may be body parts e.g. feet or even the chair a person is sitting in. 


what factor effect the balance of an object

Mass of the object
Size of the base of support (BOS)
Height of the centre of gravity (COG) above base of support
Position of line of gravity (LOG) relative to base of support
Increasing BOS in direction of oncoming force
Positioning COG near edge of BOS in direction of oncoming force