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foundation of biomechanics Flashcards

1
Q

Pythagoras theorem?

A

A^2 + B^2 = C^2

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2
Q

Formula for finding out angles and lengths in a right angled triangle?

A

SOH CAH TOA

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3
Q

How to label a triangle?

A

Hypotenuse will be the diagonal
Adjacent will be side next to angle which isn’t the hypotenuse
Opposite will be side opposite from angle you are looking at?

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4
Q

How can triangle formulas be used to find distance traveled by ball?

A

Draw right angle triangle, will be given angle and vertical velocity or horizontal velocity and just work it out using formula

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5
Q

Qualitative analysis is?

A

Description of movement

Requires experienced coach

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6
Q

Quantitative analysis?

A

Numerical evaluation based on data collected during motion

Allows assessment of aspects which can’t be observed eg. force

Removes subjectivity

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7
Q

What is kinesiology?

A

Scientific study of human movement

Mainly qualitative

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8
Q

What is biomechanics?

A

Considered to be more quantitive

Derived from mechanics, involves motion and effect of forces on living organisms

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9
Q

2 types of motion present in human movement or object propelled by a human?

A

Linear (translational) - motion along a straight or curved pathway in which all points on a body/object move the same distance in the same amount of time

Angular - motion about a given point so that different regions of the same body part/region do not move through the same distance in a given time.

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10
Q

What is kinematics?

A

Characteristics of motion from a spatial and temporal perspective

Without references to forces causing the motion

Variables of interest are therefore position, velocity and acceleration

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11
Q

What is kinetics?

A

Area of study that examines forces acting on a system (human body or an object)

The forces can be external (ground reaction force)

Internal (muscle and bones)

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12
Q

What’s a static system?

A

Systems that aren’t moving, or moving at a constant speed

So it’s in equilibrium

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13
Q

What’s a dynamic system?

A

Systems that are being accelerated

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14
Q

What’s sagittal plane?

A

Cut through the middle of pecs

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15
Q

What’s transverse plane?

A

Cut through belly button (rubber ring around you)

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16
Q

What’s frontal plane?

A

Cut across shoulders

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17
Q

What’s rectilinear translation?

A

Body travels in a straight path

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18
Q

What’s curvilinear translation?

A

Body travels in a curved path

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19
Q

What is the sampling frequency?

A

Number of pictures per second (frames/fields)

Units = Hz

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20
Q

What is digitisation?

A

Giving selected points numerical values allowing linear and angular displacements of joints and anatomical landmarks to be determined

This allows the calculation of velocities and accelerations

Effectively turns a qualitative video into a quantitative one

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21
Q

What is scaling?

A

Conversion of measured distance into real units

To work this out from screen to reality

Find out what 1mm is on the screen in metres by dividing in reality by mm on screen

Then multiply what your value is by the amount of mm if you asked a different length

Always make sure answer is in metres

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22
Q

Difference between distance and displacement?

A

Distance is the length of the path that it follows

Where as displacement is the length of a straight line joining its initial and final positions, taking note of the direction of this line

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23
Q

What is speed?

A

speed = distance / time

Scalar quantity

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24
Q

What is velocity?

A

How fast an object moves and in which direction

Velocity = displacement / time

So velocity = change in position / change in time

Vector quantity ( magnitude and direction)

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25
Equation for the first central difference method?
Vx2 = (x3 - x1) / (t3 - t1) Essentially velocity = (Final x position - starting x position) / (final time - initial time) units of velocity is m/s or m.s^-1 Use values either side of the one your trying to find at a specific time point With new values for velocity can do this again to find out acceleration
26
What is acceleration?
a = change in velocity / change in time So basically = (final velocity - initial velocity) / (final time - initial time) Units are m.s^-2
27
What is uniform acceleration?
Rate of change of velocity is constant So acceleration is constant
28
Value of gravity?
9.81 m.s^-2
29
Equations for uniform acceleration?
``` u= initial velocity v = final velocity s = displacement of the object a = acceleration t = time ``` ``` v = u + at v^2 = u^2 + 2as s = ut + 0.5at^2 ```
30
Does mass influence motion in flight?
NO
31
If an object is moving upwards it's acceleration is and if it's moving downwards?
a = -g = -9.81 m.s^-2 Air resistance assumed to be negligible a = g = 9.81 m.s^-2
32
Theory on motion of flight?
An object will take the same amount of time to reach max height to then reach floor again Time up = time down
33
When an abject is in flight do we consider the vertical and horizontal components separately?
Yes Equations apply to both
34
How to answer a question when you need to use horizontal and vertical velocity?
Work out flight time, using vertical component Work out with acceleration, initial velocity and the final velocity being 0, but remember need to multiply the flight time by 2 to find full value Now can work out the unknown you want
35
What is the resultant velocity composed of?
Vertical and horizontal velocity Worked out with Pythagorus and SOH CAH TOA
36
What angle in theory gives optimum range in a projectile?
45 degrees
37
What does a greater vertical velocity component consist of?
Greater Height Greater flight time Greater range
38
What does a greater horizontal velocity consist of?
Same height Same flight time Greater range
39
What is inertia?
The resistance of a body to motion
40
What is mass?
The amount of matter makes up a body Greater mass = greater inertia Standard unit is kg
41
What is force?
The cause of motion Alters, or tends to alter, a body's state of rest or uniform motion Unit = Newtons (N) 1 N accelerates a 1 kg mass by 1m.s^-2
42
What is a vector?
Provides magnitude and direction
43
What is Newtons law of gravitation?
F ∝ (m1 x m2 ) / d^2 F = force acting on each particle m1 = mass of first object m2 = mass of second object d = distance between the mass centres
44
Features of weight?
Weight = Mass x gravity Weight varies slightly depending on location (as distance to centre of earth varies) Unit is newtons
45
What is Newton's first law of motion?
Everybody continues in a state of rest, or uniform motion in a straight line, unless compelled to change that state by external forces exerted upon it
46
What is Newtons second law of motion?
Force = mass x acceleration
47
Newton's 3rd law of motion?
For every force that is exerted by one body on another, there is an equal and opposite force exerted by the second body on the first
48
In a vertical Ground Reaction force graph for running, what's is the small increase, and the highest point and scalings?
Peak impact force is the small increase in bell curve Peak active force top of bell curve 0.3 seconds on x axis Around 2500 N on y axis
49
Features of horizontal GRF for running?
Symmetrical goes negative then positive (sideways figure of 8) Peak braking force is smallest value Peak propulsive force is highest value It's the same for walking but obviously time increases 0.3 seconds on x axis Around 400 N on y axis
50
Features of vertical GRF for walking?
"M" shaped Time has increased
51
What does running with a forefoot stride potentially suggest? (promoted from being barefoot)
Reduce risk in injury as there isn't the peak impact force (it's not as prominent)
52
Factors that affect GRF?
``` Speed Mass Surface Type of running technique Footwear ```
53
Equation for momentum (P)?
Momentum (kg.m.s^-1) = mass (kg) x velocity (m.s^-1) Vector quantity so has magnitude and direction
54
Total momentum of a system =?
Sum of the momenta of all the particle in the system
55
What is newtons law of inertia?
An object/system will remain at rest or un uniform motion in a straight line unless acted upon by an external force
56
Law of the conservation of momentum?
Doesn't change unless an external force act upon it
57
2 types of collisions?
Elastic collisions - kinetic energy of the system is conserved - very uncommon Inelastic collisions - kinetic energy is transferred to another form of energy Total system momentum is conserved during collisions So momentum before the collision = momentum after collision
58
How to work out the momentum of a system and then the final velocity of the system?
Work out Total momentum of system by summing all the individuals momentum's taking into account direction Then add all the masses and rearrange for the system velocity
59
Equation for force involving momentum and time?
Force (N) = (mass (kg) x change in velocity) / change in time Force (N) = Change in momentum / Change in time
60
What does impulse equal, therefore how do we increase it?
Impulse (N . s) = Change in momentum = Mass x (v-u)!!!!!!!!!!!!!!!! = Force x time over which force was applied Increase force Increase time over which the force is applied
61
Describe horizontal force and impulse in running?
Initially there is a negative horizontal impulse and braking, then mid stance switches to a positive horizontal impulse which is propulsive Impulse = area under the force-time curve if plotted So total net impulse = positive + negative impulse (negative horizontal impulse is negative on graph) If impulse = 0, then there is no change in impulse so the person is moving at a constant speed Also if positive is larger then speeding up, if negative is larger then we are slowing down
62
Given impulses and mass how do you work out how high someone has jumped?
Find net impulse in N.s Look at second half of jump so time is halved Use Net impulse = mass x v (as u will be 0) Now know u so can input into Suvat to work out s or if don't need to use impulse can just imput the second half of the jump into s = ut + 0.5at^2
63
Equation for pressure?
Force(N) / Area (m^2) Units = Pascals = N . m^-2
64
Equation for mechanical work?
Work(J) = Force (N) x Displacement (m) 1 joule = 1 Nm
65
What is positive work?
When the displacement is in the same in the same direction as the force of interest
66
What is negative work?
When the displacement is in the opposite direction of the force of interest Joules value will be negative as well
67
What is the total system work?
= Sum of positive (normally work done by muscle) and negative work (normally work done by gravity) Can be Simplified to: W = d(f -mg) ``` w= total system work d = displacement f = force m = mass g = gravity ```
68
What's the value for mechanical work if an object isn't moving?
0
69
Why is work done not a very accurate measure?
It doesn't consider time
70
Equation for power?
It's the rate at which work is performed Power = Work / time Units = J.s^-1 = Watts (W) Or Power = Force x velocity
71
Equation for kinetic energy and definition?
Energy resulting from motion KE = 1/2 x mass x velocity^2
72
Equation gravitational energy and definition?
The energy an object posses because of it's position in a gravitational field. We will usually think of this as an objects height from the ground PE = mass x gravity x height
73
Equation for strain energy and definition?
Stored potential energy in a object which is deformed by a force SE = 1/2 . k . x^2 (using "." for multiplication) k = stiffness (N/m) x = displacement (m)
74
A way to find total mechanical energy?
= KE + PE +SE
75
At the apex of a projectiles flight the potential energy will be?
All of the total energy of the system
76
2 types of friction?
Sliding | Rolling
77
What's force applied (P), friction force (F) and reaction force (R)?
``` P = the force pushing F = force resisting (limiting friction is the highest value it can take in the circumstance) R = perpendicular to contact surface (normally straight up) ```
78
Equation for friction force is equal to?
The reaction force (R) multiplied by a constant (u) F = uR F/R = u
79
Does mass and surface area affect friction?
NO
80
What does the constant (u) equal when you have been given an angle in which something starts to slide?
u = tan(x)
81
Equation for friction force in sliding friction?
Fs (friction force) = coefficient of sliding friction (us) x R (reaction force) Coefficient of sliding friction < coefficient of limiting friction
82
What does Fy/Fz equal?
u
83
Equation for the coefficient of restitution?
Giving you e = square root of (height bounced /height dropped)
84
Other factors that can increase e?
Temperature
85
What increases force of attraction?
Smaller distance between objects | Larger masses
86
What's the line of gravity?
Is the vertical line through the point at which the object would balance
87
What's the centre of gravity (means the centre of mass as well)?
Where the 2 lines of gravity (horizontal and vertical) meet = the point about which gravitational force is balance it is the point through which the resultant force acts
88
3 ways to determine the centre of gravity?
Balance method Suspension Reaction board
89
5 ways to asses sports performance?
Direct observation Video observation Video analysis to obtain kinematic data Force analysis to obtain kinetic data with a force plate Pressure analysis to obtain kinetic data with a pressure plate
90
How to answer a large study question?
Introduction: What is the question you are trying to answer? Why would it be beneficial to investigate this? Population: How many participants would you use? How would you determine the inclusion/exclusion criteria? Equipment: What equipment would be required? Can you add extra information such as make/model and recording frequency? Experimental setup ``` Testing procedures: What would happen? Conditions? Repeat trials? Order? ``` ``` Data collected: What type (kinematic or kinetic)? Which variables would be of interest? ``` Implications: What does the data tell you? How does it relate to the question you were trying yo answer
91
How to draw a Standing vertical jump impulse and answer the question about working it out?
y axis goes up to 3.5 seconds x axis goes up to 2500 N In comparison to BW line, straight line for a bit, small down, big bump little bump, straight down to touch x axis, big gap, massive straight up, down through BW line then up to bw line and wiggle Take up is on left side of gap on axis, landing is on right side Peak take off force is top of hump before drop down and peak landing force is top off hump on right side Negative take-off impulse is area of the dip at the beginning, and positive is the area above the BW line on the next bit Have force time history printed onto gridded paper from the force plate Calculate what one mm^2 is in N.s (0.5 N.s) Net impulse = 100 squares in negative (-50 N.s) + 600 squares (300 N.s) = 250 N.s Impulse = mass x final velocity ``` 250 = 100v v = 2.5 ``` ``` 2.5 = 9.81t t = 0.255 ``` s = (0 x 0.255) + (0.5 x 9.81 x 0.255^2) = 0.32 m
92
Different foot arches on a pressure plate?
High Arch: Only visible is toes and ball of foot Medium Arch: Just a normal foot toes are visible Low arch: Broader foot can only see big toe
93
Software used in digitising?
MaxTRAQ
94
Software used when we measured a punch?
Codamotion software
95
Describe steps in a friction experiment looking at turning?
Use the AMTI Force platform to obtain vertical and anterior-posterior force time histories at 500Hz during turning From the anterior-posterior need the values of: Peak Braking force Time of peak braking force Then from vertical: Vertical force at time of peak braking force (N) The put into the equation: Coefficient of friction = Fy/Fz = Peak braking force / Vertical force at the time of peak braking
96
Describe steps in working out friction between a shoe and a surface?
Place shoe on a surface and slowly raise until find a point in which shoes starts to slide, find just before this point and measure the angle with a goniometer Then use the equation u = tan(x)
97
When walking instead of walking what does it do to the scaling force?
Halves it roughly
108
How do you get mass in vertical jump and what do you call grid?
Create scaling factor Calculate mass from body weight line (/9.81)

Human Biosciences (69 decks)

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