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Pe- Anatomy and Physiology > Biomechanics > Flashcards

Biomechanics Flashcards

1
Q

When does linear motion occur?

A
  • When a body moves in a straight or curved line with all parts of the body moving the same distance in the same direction at the same speed.
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2
Q

Force definition

A
  • A pushing or pulling effect on an object
  • An object at rest can be changed by the pushing or pulling effect of another object
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3
Q

Quantities of linear motion:

A
  • Vector quantity
  • Scalar quantity
  • Velocity
  • Inertia
  • Acceleration
  • Mass
  • Speed
  • Displacement
  • Momentum
  • Weight
  • Distance
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4
Q

Scalar quantity

A
  • A quantity which is fully described by magnitude alone
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5
Q

Vector quantity

A
  • A quantity which is fully described as both a magnitude and a direction.
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6
Q

Mass definition

A
  • The quantity of matter a body possesses
  • Always remains the same at any place
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7
Q

How does mass get bigger?

A
  • The greater the density and volume of the body the greater the matter and therefore the mass.
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8
Q

What is weight?

A
  • Force exerted on the mass of a body by gravity
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9
Q

What is weight measured in?

A
  • Newtons as it’s a force
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10
Q

Is weight a scalar or vector quantity?

A
  • Vector quantity
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11
Q

How is weight a vector quantity?

A
  • As weight always acts downwards from the centre of mass it has direction as well as magnitude.
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12
Q

How is direction and magnitude signified?

A
  • Direction is signified by an arrowhead
  • Magnitude is signified by the length of the arrow
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13
Q

Is mass a scalar or vector quantity?

A

Scalar quantity

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14
Q

Weight force equation?

A

Mass x gravitational field strength

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15
Q

What is the Gravitational field strength on earth?

A

9.8

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16
Q

What is inertia?

A
  • The reluctance of a body to move or change it’s state of motion
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17
Q

How does mass and inertia link?

A
  • The bigger the mass of an object the harder it is to move or change it’s motion and therefore the larger it’s quantity of inertia
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18
Q

Distance definition

A
  • A measure of the path a body takes in moving from one position to another, measured in metres
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19
Q

Displacement definition

A
  • The shortest possible route between the starting and finishing point of a body that has moved
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20
Q

What is the difference between distance and displacement?

A
  • The quantity of distance refers to the amount of ground an object covers during it’s motion
  • But displacement considers how far the position of the object has changed as a result of the motion.
  • Distance is a scalar quantity but displacement is a vector quantity
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21
Q

Speed definition

A
  • A body’s movement per unit of time with no consideration for direction
  • Measured in (ms-1)
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22
Q

Is speed a scalar or vector quantity?

A

Scalar quantity

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23
Q

Speed equation

A

Speed (ms-1)= Distance (m)/ time (s)

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24
Q

Definition of velocity

A
  • The rate of change of displacement
  • Speed of a body in a given direction
  • Measured in (ms-1)
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25
Q

Is velocity a scalar or vector quantity?

A

Vector quantity

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26
Q

Velocity equation

A

Velocity (ms-1)= Displacement (m)/ Time (s)

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27
Q

Acceleration definition

A
  • The rate of change of velocity of an object
  • Measured in (ms-2)
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28
Q

Is acceleration a scalar or vector quantity?

A

Vector quantity

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29
Q

Acceleration equation

A

Acceleration (ms-2)= change in velocity (ms-1)/ time (s)
(Vf-Vi)
———
T

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30
Q

Momentum definition

A
  • Momentum is the amount of motion a body possesses and is the product of mass and velocity
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31
Q

Momentum equation

A

Momentum (kgms-1)= mass (kg) x velocity (ms-1)

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32
Q

What are changes of momentum as a result of?

A
  • A change in velocity as mass remains constant
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33
Q

Impulse definition

A
  • Impulse is concerned with the length of time a force is applied to an object or body and relates to a change in momentum that occurs as a consequence
34
Q

Impulse equation

A

Impulse= force x time

35
Q

What is a change in momentum synonymous to?

A

Change in acceleration

36
Q

What is impulse equal to?

A

A change in momentum

37
Q

What are the 2 reasons impulse is used in sporting activity?

A
  • Add speed to a body or object
  • Slow down moving bodies slowly on impact
38
Q

When will acceleration occur?

A
  • When the positive impulse exceeds the negative impulse
39
Q

When will constant velocity occur?

A
  • When positive and negative aspects of impulse are equal.
40
Q

When will deceleration occur?

A
  • When the negative impulse exceeds the positive impulse
41
Q

Newtons 1st law (law of inertia)

A
  • Everybody at rest, or moving with constant velocity in a straight line, will continue in that state unless compelled to change by an external force exerted upon it.
42
Q

Newtons 2nd law- Law of acceleration

A
  • F= ma
  • Acceleration of a body is proportional to the force causing it and takes place in the direction in which the force acts.
  • greater force= greater acceleration
43
Q

Newtons 3rd law- Law of action and reaction

A
  • Object applies a force upon another object, there is a force equal in magnitude but opposite in direction exerted by the second object on the first
44
Q

What happens when force is applied to an object?

A
  • The velocity of that object changes constituting an acceleration
45
Q

What can a force do?

A
  • cause a body at rest to move
  • cause a moving body to accelerate
  • cause a moving body to decelerate
  • cause a moving body to change direction
  • cause a body to change shape
46
Q

When do balanced forces occur?

A
  • When 2 or more forces are in operation that are equal of size but opposite in direction
  • All the forces cancel each other out so that there is zero net force
  • An object or body will either remain stationary or if moving will continue to do so at constant velocity
47
Q

When do unbalanced forces occur?

A
  • Where a force acting in one direction is larger than that acting in the opposite direction
  • Object/ body will start to move or accelerate/ decelerate in the direction of the bigger force
48
Q

Net force definition

A
  • The resultant force acting on a body having considered all other factors acting.
49
Q

Vertical forces

A
  • Weight
  • Reaction force
50
Q

Weight force

A
  • weight= mass x gravity
  • always acts downwards from the centre of mass of an object towards the centre of the earth
51
Q

Reaction force

A
  • Always occur whenever two bodies are in contact with one another
  • Will always act at right angles to the contacted surface
52
Q

Horizontal forces

A
  • Friction (thrust in water)
  • Air resistance (drag in water)
53
Q

Friction definition

A
  • A resistive force encountered when two or more bodies in contact move past one another
54
Q

Factors affecting friction

A
  • Roughness of surfaces in contact- the rougher the surfaces the greater the friction
  • The greater the down force/ mass of an object the greater the friction
  • Warmth of surfaces
55
Q

Air resistance definition

A
  • The force of air pushing against a moving object, it is a form of fluid friction that acts on something moving through the air
56
Q

Factors affecting air resistance

A
  • Velocity of moving object (the faster an object is moving the more air resistance there is going to be)
  • Frontal cross-sectional area of the moving body (the larger the frontal cross sectional area the greater the effects of air resistance)
  • Shape and surface characteristics of the moving body (the less streamlined and rougher the surface of the moving body the more it will be affected by air resistance)
57
Q

What are free body diagrams?

A
  • they are diagrams used to show the relative magnitude and direction of all the forces that are acting upon an object or body in a given situation
58
Q

What is a projectile?

A
  • Not in contact with the floor (got to be in air)
  • Said to have both a vertical and horizontal velocity
59
Q

How can changes to the velocity of the projectile be explained?

A
  • By air resistance as gravity remains constant
60
Q

What are the 2 forces that can affect the projectile?

A
  1. Gravity
  2. Air resistance
61
Q

Factors affecting the horizontal displacement of a projectile?

A

. Velocity of release (increase in velocity of projectile will increase the horizontal displacement)
. Height of release (increase in height of projectile will increase the horizontal displacement)
. Angle of release (if the release and landing height are equal the optimum angle of release is 45 degrees) e.g. pass in football

62
Q

If the release height is greater than the landing height what is the optimum angle?

A
  • less than 45 degrees (shot put)
63
Q

If the release height is less than the landing height what is the optimum angle?

A
  • greater than 45 degrees (bunker shot in golf)
64
Q

How is a steep parabola produced?

A
  • When the vertical component is much larger than the horizontal component
65
Q

How is a less steep parabola produced?

A
  • When the horizontal component is greater than the vertical component
66
Q

What is angular motion?

A
  • Occurs whenever a force acts outside the centre of mass of body or object (eccentric force) and is necessary if rotation is to occur. E.g. gymnast performing a back flip will lean backwards just before take off)
67
Q

Definition of eccentric force

A
  • A force applied outside the centre of mass of an object or body. (Causes angular motion).
68
Q

Moment of inertia (definition)

A
  • A measure of the resistance of a body to change it’s state of angular motion (rotation) (measure in kgm2)
69
Q

Factors depending on moment of inertia

A
  • mass of object (greater mass the greater the moment of inertia)
  • distribution of mass from the axis of rotation (further the mass is distributed away from axis of rotation the greater the moment of inertia
70
Q

Angular velocity definition

A
  • angular displacement travelled in a specified time
71
Q

Relationship between angular velocity and momentum of inertia?

A
  • inversely proportional
  • moi x av= ang momentum
  • when a object is rotation its momentum is conserved
  • if moi is altered it will affect the velocity
  • e.g. if a spinning skate beings their arms outwards av will decrease
72
Q

Angular momentum equation

A

Moment of inertia x angular velocity

73
Q

Law of conservation of angular momentum

A
  • angular momentum can’t be changed during flight
  • MOI and angular velocity are inversely proportional
  • Decreasing moment of interia (arms close to body) increases angular velocity
74
Q

What does fluid mechanics refer to?

A

Gas/liquid
Both oppose motion

75
Q

Bernoulli principle

A
  1. Air flow above the foil has to travel a further distance so its speed must increase. So the pressure here is low.
    Air flow below the foil has to travel a relatively shorter distance so its speeds will be slower. So the pressure here is high
  2. When there are two contrasting pressure concentrations close to each other, this is known as a pressure gradient
  3. When this exists air will always move in the direction of high-low
76
Q

Magnus effect

A

Back spin
1. The air lines above the ball are moving with the direction of the spin causing the air speed to increase
2. The air lines below the ball are opposing the direction of the spin causing the air speed to decrease
3. This creates a pressure change
4. Back spin causes high pressure beneath the ball and low pressure above the ball
This creates an upwards force
5. Top spin causes high pressure on the top of the ball and low pressure on the bottom creating a downwards force

77
Q

Drag

A
  • Same as air resistance
  • It opposes motion
  • Describes the friction of air molecules acting on an object
78
Q

Laminar flow

A
  • Describes the smooth flow of air (or water) past an object
  • Laminar means flowing in layers
  • Happens at low speeds
79
Q

Turbulent flow

A

(High drag)
- air resistance is greater
- happens when laminar flow is interrupted either by going too fast or by a protrusion then the air is thrown out into vortices, the layers mix up and this is turbulent flow

80
Q
A

Pe- Anatomy and Physiology (8 decks)

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