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Pe Studies Year 12 > biomechanics > Flashcards

biomechanics Flashcards

1
Q

benefits of biomechanics

A
  • Improve technique efficiency
  • Injury reduction through an understanding of injury causes and application of correct technique
  • Modification of sports equipment to improve sports performance at all levels
  • Technological development of equipment and computer technology to assist in transition from practice field to playing field
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2
Q

Newtons 1st law of motion

A
  • A object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force
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3
Q

Newtons 2nd law of motion

A
  • The rate of change of acceleration to a body is proportional to the force applied to it, and inversely proportional to the mass of the object
    FORCE = MASS x ACCELERATION
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4
Q

momentum

A

acceleration/momentum
M = mass x velocity
- An object can only have momentum if it is moving
- The greater the momentum, the more force that needs to be applied to either stop or slow the object down

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5
Q

conservation of linear momentum

A

principle states the total momentum of two objects before and after impact are equal.

  • This occurs in situation where a perfectly elastic collision takes place (when no energy is lost to sound and heat)
  • The momentum of one object is transferred on contact to the other object (momentum is not lost just transferred) resulting in no change in total momentum, rather a transfer of momentum
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6
Q

Newtons 3rd law of motion

A
  • For every action, there is an equal and opposite reaction
  • When two objects exert a force upon each other, the forces are opposite in direction and equal in magnitude
  • The law directly applies to the concept of conservation of momentum
  • The 3rd law explains that when collision occur, an equal an opposite force occurs resulting in a transfer of momentum from one object to the other
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7
Q

impulse

A

change in momentum of an object
Impulse = force (mass x acceleration) x time (the length of time over which the force is applied)
- The longer the force can be applied to an object and the greater the size of the force applied the greater the objects impulse
- Impulse is important in impact/collision situations

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8
Q

Coefficient of restitution (COR):

A

measures the elasticity of the collision between an object and a given surface.

  • It measures how much energy remains in the object after a collision takes place
  • Measure of how much rebound exists following a collision
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9
Q

2 types of COR

A

A COR of 1 represents an elastic collision (when a ball is dropped from a given height the ball will rebound to the same height after colliding with the ground)
A COR of 0 represents an inelastic collision (when the ball is dropped, it doesn’t bounce at all)

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10
Q

how do you calculate the COR

A

square root of height bounced/height dropped

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11
Q

factors affecting COR

A
  • equipment and material
  • temperature of balls
  • the velocity of the collision
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12
Q

concentric force

A

face applied to produce linear motion. e.g. hitting a flat serve in volleyball

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13
Q

eccentric force

A

off centre force applied to produce angular motion

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14
Q

forces that create angular motion

A
  • angular rotation

- when only 1 eccentric is applied to the object

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15
Q

how do you increase angular rotation

A
  • increase the amount of force applied

- increased the distance from the axis by which the force is applied

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16
Q

force couples

A

when two but oppositely directed forces act on opposite sides of an axis of rotation
- this causes the force that produce linear motion to cancel each other out, causing the object to rotate in the fixed position

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17
Q

torque

A 
T = F x D 
T = moment force 
F = force measured in newtons 
D = distance the force is applied over measured meters
magnitude of the turning force

The magnitude of the turning force is torque

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18
Q

moment arm

A

the distance between where the force is applied and where the torque is produced is called the moment arm. The longer the moment arm the greater the rotational force produced

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19
Q

angular momentum

A

the quantity of angular motion possessed by a rotating body

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20
Q

moment of inertia

A

mass of the object x radius of rotation
e.g. by moving the mass of the object further way from the axis of rotation, you are increasing its radius of rotation and hence increasing its moment inertia

21
Q

conservation of angular momentum

A

means that a spinning body will continue spinning indefinitely unless an external force acts on it

22
Q

3 main parts of levers

A
  • weight or resistance to be moved
  • axis or pivot point
  • application of fore to move the weight or resistance
23
Q

functions of levers

A

1- increase application of force by making the force arm longer than the resistance arm
2- increase the speed of movement by making the force arm shorter than the resistance arm

24
Q

parts of levers

A

fulcrum/axis: point around which the lever rotates
effort force arm: the distance between the fulcrum and the point at which the force is applied
resistance arm: the distance between the fulcrum and the centre of resistance
input: force exerted on the lever
output: force exerted by the lever

25
Q

first class lever

A 
in 1st class levers the axis/fulcrum is located in the middle with the force and resistance either side
example: see saw
26
Q

second class lever

A

the axis/fulcrum is located at the end with the resistance in the middle and force applied at the opposite end
example: wheelbarrow, push up

27
Q

third class lever

A

the axis/fulcrum is located at one end with the application of the force in the middle and resistance applied at the opposite end

  • most common type of lever in the human body
    example: bicep curl
28
Q

factors that affect the use of levers

A

1- length of the lever
2- the inertia of the lever
3- the amount of force

29
Q

lever principles

A
  • a smaller force can balance a larger resistance when the force arm is longer than the resistance arm
  • a force can move a resistance through a greater range of motion when the force arm is shorter than the resistance arm
30
Q

types of fluid that can alter performance

A

1- water

2- air

31
Q

major fluid forces

A

1- drag
2- lift
3- buoyancy

32
Q

fluid resistance

A
  • an object movies through a fluid, it disturbs it

- the greater the disturbance to the fluid the greater the transfer of energy from object to fluid

33
Q

factors that affect fluid resistance

A

1- density

3- viscosity

34
Q

surface drag

A

friction produced between the fluid and the surface of a moving object

35
Q

factors affecting surface drag:

A

1- relative velocity of moving object
2- relative roughness of surface object
3- viscosity of the fluid
4- surface area of the object

36
Q

factors affecting form drag

A

1- cross sectional area of the object presented to the fluid
2- velocity of the object
3- surface roughness
4- shape of the object

37
Q

wave drag

A

resistance formed by the creation of waves at the point where and air and water interact

38
Q

factors affecting wave drag:

A

1- relative velocity of the wave
2- technique
3- open water vs closed conditions

39
Q

form drag

A

resistance created by pressure differential between front and back of an object moving through a fluid

40
Q

boundary layer

A

the layer of air surrounding or attached to the ball
Laminar- smooth flow, large turbulent pocket at back of the ball
Turbulent- rough flow, small turbulent pocket at back of the ball

41
Q

boundary layer separation

A

where boundary layer breaks away from the ball

- the earlier the boundary layer separation the greater the pressure gradient between the back and front of the ball

42
Q

factors affecting boundary layer separation point

A

1- velocity

2- surface roughness

43
Q

factors affecting drag non environmental factors

A 
1- drag coefficient 
2- cross sectional area 
3- speed
4- surface roughness 
5- mass 
6- shape
44
Q

environmental factors affecting drag

A

1- air density
2- atmospheric pressure
3- humidity
4- temperature

45
Q

lift forces

A

refers to the componenet of force that acts perpendicualr to the direction force. Only occurs in objects that are spinning or not symmetrical

46
Q

Bernoullis principal

A

states that velocity is inversly proportional to pressure
or
that an increase in the speed of fluid occurs simulatnaously with a decrease in pressure

47
Q

Magnus affect

A

term used to describe the effect of rotation on an objects path as it moves through a fluid
it applies to bernoulis principle to explain the effect spin has on the trajectory or flight path of an object

48
Q

biomechanical principals

A
  • balance
  • coordination continumm
  • force motion
  • force time
  • inertia
  • optimal projection
  • range of motion
  • segmental inertaction
  • spin

Pe Studies Year 12 (7 decks)

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