Kinetics (M2) Flashcards
what is torque influence by
magnitude of the force
direction
point of application of force
what is the equation for torque
T=Fr
when the sum of all torque acting on a joint are equal to 0 what does this mean
static at point of equilibrium - balance
what is the equation for bending moment
M=Fx
(force applied to the beam multiple by distance)
anti clockise is what direaction for right hand rule
positive
to accelerate an object what things do you need to have angular rotation
- force applied off centre
- torque
what is the formular for mass moment of inertia
I= mr^2
what does mass moment of inertia only explain
how difficult or easy a movement may be considering the distribution of mass about the axis of rotation
who is more likely to have more momentum - beaudan barrett or sam whitlock. some one that has more mass or less mass, when travelling at the same speed
Sam whitelock - someone that has more momentum
what is the formular for angular velocity
H= mr^2*w
what 3 things affect angular momentum
- Mass
- Distribution of mass with respect to axis of rotation
- Angular velocity of body
Why is total momentum system conserved during angular rotation in the air
gravity acts through the CoM, therefore doesn’t cause momentum
T/f angular momentum can be transferred from one axis of rotation to another
true
how does a long jumper is able to stray up right, because when they take of they have a forward momentum that courses them to rotate forwards
Transfer of moment from com to the limbs (rotate) so body stays up right
how do we alter the axis of rotation in the air
make axis off centre (so it doesn’t go through Centre of mass) e.g. have one arm up
what is the resistance of a body to rotate called
mass moment of inertia
how does an athlete generate angular rotation
by applying a rotational force to the body
during running when do you reach peak velocity
in max velocity phase
when acceleration is 0
what are the 4 phases of running
- drive
- transition
- max velocity
- maintainece
what makes a good runner (usain bolt)
able to hold max velocity for longer
what is the term radius of gyration
when dealling with segment of masses where axis of rotation is not located through the centre of mass
what is the concept of work
use force to move an object
how do you calculate work
W=F*s(cos(theta))
what is the concept of power
P=Work/time
Power is limited by the rate of what
ATP
what curve limits power
Force-velocity curve
why does it take longer to perform max rep
more muscles are need to move heavier weight, takes longer for them to contract
what can joint power determine
the product of net torque and the joint angular
when will power be positive - what are the signs for angular velocity and angular acceleration - what is this referred to
same
power production
what does power production mean for energy flow direction
muscle to arm segment
power absorption mean for energy flow direction
arm segment to muscle
what is newtons first law
object will remain at rest or constant velocity unless external forces act on it
what is the equation for force - newtons 2nd law
F=ma
newtons 3rd law
for every action there is an equal to opposite reaction
what quantity is force
vector (has both magnitude and direaction)
what is the net force
sum of all force
what are the 5 steps to drawing a free body diagram
- identify the system
- separate the system
- identify COM
- identify external forces
- find resultant of forces (by using pytha)
what does CoP (centre of pressure) mean
average pressure point beneath the foot or feet
what are the gait objectives
- propel body forwards
- efficiently - minimal energy expenditure
in the 1st peak of normal walking what should x the persons body weight
1.2
the 1st peak (F1) if this is lower what can it tell about the person
the are less confident or slower walker
in the trough what is the x to the persons body weight
0.6
in the trough (F2) if its deeper what does this signify
if they are moving quickly though movement
what does a low peak in the 2nd peak (F3) mean
individual has poor ability to propel their body forwards
what is the claw back
the initial spike in walking diagram
- clawing toes into ground like a peginuin
what % of stance phase does cross over
55%
what 3 components is the resultant GRF made up of
1/ vertical
2. anterior -positor
3. medial -lateral
what do pedotti digrams rely on
information provided by the force plate
wht 3 things do you need to construct a pedotti diagram
- vertical force
- horizontal force
- position of center of pressure
what is inertia
resistance to change motion state
what is the equation for momentum
L=Mx V
How do you maximise performance with anterior -posterior impulse (e.g. long jump
- gaining initial momentum from run up
- minimising loss of momentum - redirecting hz motion into vt motion
does a force through COM generate linear motion
yes
when force is not applied to the COM of the ball
- what force does this create
- what is this
- what motion (linear or angular)
eccentric force
torque
linear and angular
what are three things torque is influenced by
- magnitude
- line of action
- point of application
what is the equation for torque
T= Fr sin (theta)
what only causes rotation in - where the objects placed
perpendicular - therefore use sin because of it
with regards to the right hand rule if is clock wise is this positive or negative
negative
what makes a successful high jump
- less mass
- largest vt force
for the fosbury flop what must an athletes create rotation around
Centre of mass
what is the equation for angular acceleration
a= T/mr2
repositioning _____ can help to alter angular acceleration
limbs
having a greater mass does this make it easier or harder to change angular velocity
harder
what does mk2 mean
radius of gyration - remote terms
e.g. mass x distance form COM^2
for a flexion extension graph every time there is a peak what does this mean for the for the velocity time curve
it will cross over the line of the velocity time curve
for a flexion extension graph every time this graph crosses the centre line what does this mean for the for the velocity time curve
change in direction for the velocity time curve
when velocity time curve has a peak what does this mean for the acceleration graph
will cross the centre line
every-time the velocity time graph crosses the centre line what does this mean for the acceleration graph
acceleration graph will have a peak
moment of inertia depends on what
axis of rotation
how do remote and local axis differ
remote = external
local = own
what does mass moment of inertia not explain
speed or velocity
what is the equation for angular momentum
H=mr2 x w
what are three things that effect angular momentum
- mass
- distribution of mass with respect to rotation
- angular velocity of the body
once airborne is it possbile for athlete to alter angular velocity by changing momentum of inertia
yes
when body rotating in air -momentum is what
conserved
why is momentum conserved in air
- no external forces
gravity acting through COM
what is angular momentum the product of
moment of inertia and angular velocity
when do you reach peak velocity - when acceleration is what
acceleration zero
having a large spiek for accerlation curve in running is associated with what
quick explosive acceleration with high peak force - often seen in world class sprinters
explain the force in the medial-lateral direction during walking
- small anterior impulse - claw
- this large posterior impulse - going below line
- this around 50% through-stance phase increases anterior impulse (goes above line)
increasing to reach peak velocity
- what happens to hz forces and
- propulsive and breaking force
- Hz force begins to decrease
- propulsive and breaking begin to equalize
object moves with sufficienctly high velocity relative to surrounding fluid, layers of fluid near surface of object mix and flow becomes turbulent of laminar
turbulent
viscosity involves _____ resistance of fluid to flow
internal
buoynacy forces act through what
centre of volume
what does the vertical force component for single step look like
M shaped
what is a special type of force diagram that is used in gait analysis
Butterfly force diagram
how do you calculate reaction force
sum of force: R - weight (9.81)
derive joint power time curve by multiplying angular velocity and angular acceleration together - what is this called
inverse dynamics
max velocity = what of KE
max KE
the net work done by all forces acting on the body equals the change in KE describes what theorem
Work-energy theorem
what contributes to the drag force
- surface friction
- form drag - reduce negative pocket
- wave drag - interface of 2 fluids
why is swimming an inefficient form of motion
deals with all three forms, more dense and viscus
what direction is lift force generated in with respect to fluid flow
perpendicular to fluid flow
explains Bernoulli’s principal in terms of velocity and pressure
high velocity flow to low pressure
what is the magnus force
lift force created by spin
what is force locking
force locking between 2 smooth materials
what is form locking
material properties of traction
what are the three aspect that create a lift force
- foil shape
- angle attack
- spin
how doe foil shape effect lift force
- fluid seperation, low pressure - high velcity over top
hoe does angle of attack effect lift force
angle of orrinetation - optimum angle of attack for maximizing range is angle at which lift/drag ration is maximum
what contributes to the drag force
- surface friction
- form - reduce negative pocket
- wave drag - interface of 2 fluids
what is the most important component of the drag force equation
velocity
what are ways swimmers can reduce drag forces
- streamlined positon as much as possible
- head down
- tight swim wear
- swim cap
- small surface area
what stroke style has the least amount of drag
freestyle
example the reverse swing
turbulent (rough side) faces the batsman. bowled fast enough (above 85mph). laminar side goes into turbulent befor reaches seam
what is Bernoulli’s equation
P + 1/2mv^2 +pgh = constant
what is the equation for work energy theory
and what is work transferred into
W=E2-E1
