Revision Lecture Flashcards
What is a time series?
A measurement of something moving constantly at however many times per second.
Typically split into key events that show key parts of the movement
Events= key movements
Phases= the middle of key events
Displacement equation?
= final position- initial position
Velocity equation?
= change in displacement/ time
(m/s)
Acceleration equation?
= change in velocity/ time
(m/s2)
Momentum equation?
= mass x velocity
=kgm/s
Laws of Motion- key parts of understanding for each law?
- no change in momentum until a force changes it
- F=ma, acceleration is proportional to the force and direction
- equal and opposite reaction- Ground Reaction Forces
Force equation?
= mass x acceleration (N)
Weight equation?
= mass x acceleration due to gravity
= x 9.81
Constant acceleration equations?
suvat
s: displacement
u: initail velocity
v: final velocity
a: acceleration
t: time taken
v= u + at
v2= u2 + 2as
s= ut + 1/2 at2
s= 1/2 (u+v) t
Moment/ torque equation?
= force x perpendicular distance
What does frame rate affect?
The blur produced when taking a photo
How many times the camera takes a pic per second
Increased frame rate= decreased blur
(but less light)- add unnatural light
What does shutter speed effect?
The light produced when creating a photo
How long the shutter is open for
Less time= less light
What is aperture?
The size of the hole of the camera
Bigger size= more light
But smaller= greater acceptable region you can film
= focal length/ diameter of hole
What is focal length?
What distance away you are focussing on- can make the camera more/ less clear
Define centre of mass?
A conceptual point where all the mass of a body can be concentrated
-Balance and CoG over Base of Support
What factors affect passive stability?
-Increasing weight
-Increasing your base of support
-Increasing the horizontal distance from CoG to base of support
-Decrease height of CoG over base of support
What are aspects of stable equilibrium?
Potential energy is at a minimum
Work must be done to change position
Tendency to return to original posture
What are the aspects of unstable equilibrium?
Potential energy is at a maximum
Little/ no work needed to change position
Small movements will force gravity line outside the base of support
What are the aspects of neutral equilibrium?
Moves but no change in potential energy
Small base of support so doesn’t matter
What are the main modifiable factors to increase stability?
Increase mass
Keep CoG withn BoS
Increase BoS
Lowering CoG
Extend BoS towards oncoming force
Shift CoG towards oncoming force
Common balance reflex mechanisms?
- Ankle strategy
- Hip strategy
- Stepping Response
- Arm Circles
Forces within projectile motion?
Vertical force: gravity
Vertical Acceleration: 9.81m/s2
Horizontal force: 0
Horizontal acceleration: 0
Angular Displacement conversions?
360 degrees= 1 revolution= 2 radians
Angular Velocity equation?
= angular displacement/ time taken
(rad/ s)
Angular acceleration equation?
= change in angular velocity/ time
=rad/ s 2
Moment of Inertia equation?
= mass x distribution of mass from axis of rotation
= kg.m2
Angular Momentum equation?
= angular velocity x moment of inertia
= kg.m2.rad/s
Evaluate the use of embedded force platforms?
Pros:
Accurate and reliable
3D force measurements
high sampling frequency and resolution
Cons: restricted to indoor use and a single step
Possibly unnatural gait pattern created- force plate targeting
Expensive
What is a triaxial accelerometer?
Measures instantaneous acceleration at rest - will measure 1g due to gravity
Usually used to measure- physical activity, intensity and “load” monitoring
+ve- cheaper than lab equipment
easy to use
often embedded in other devices
can monitor close to sight of intrest
-ve- valid for intended purpose ?
affect the movements being monitored?
battery life and comfort?
Impulse equation?
Impulse (N)= FORCE X TIME
impulse= change in momentum
Rate of force development equation?
Rate of force development= change in force/ time taken
Force Development= VALR- vertical average loading rate - 20-80%
VILR- vertical instantaneous loading rate- max
Define and give the equation for friction?
A force that acts in opposition to the movement of one surface over the other
Friction force= friction coefficient x normal force
What are the main factors that affect drag force?
Dans, Van, Can, Swim
Density of fluid
Velocity- relative velocity
Coefficient - drag coefficient
Surface area- must be streamlined
Laminar flow?
Decreases resistance to movement
-Fluid slides smoothly over
-Layers flow in parallel
-Little disruption to fluid
Turbulent flow?
Increases friction
-less orderly/ predictable
-greater impact on object- slows
-boundary layer composed of vortices that increase surface friction
What are the three main ways that drag can be decreased?
- smaller surface area
-slower relative velocity
-more streamlined shape
What are the constraints to movement/ motion?
Movement Pattern- general series of anatomical movements that have common elements/ special configuration
Skill- when a general movement pattern is adapted to a task
Technique- when a skill/ task is performed
Style- individual modifications- eg: individual timings
Rules and environment- rules may guide/ penalise natural movement- discuss swing
Human factors- strength, speed, genetics
What are the six steps taken when gathering information?
- Determine the objective of the skill
- Note any special characteristic of the skill
- Study elite performances of the skill
- Divide skill into phases
- Divide skill into key elements
- Understand the mechanical reasons that each element is performed as it is.
