Unit 3 AOS 1 - Biomechanics Principles Flashcards
What is Biomechanics
Biomechanics is the science that studies living things from a mechanical perspectives, tot analyse human movement
Quantitative
uses numbers to anaylise movement (km/s, meters per second, newtons of force
Qualitative
uses a description of the quality of the performance (to much, not enough, to slow, to fast
Kinematics - describing
study of describing movement
kinetics
study of forces that course motion
linear motion
all body parts are moving together in the same direction in a straight or curved line (such as running)
Angular motion
an object or body part moves around a fixed axis
Projectile motion - leave ground
when a body or object leaves the ground and is affected only by the force of gravity and air resistance (doing a jump serve in volleyball - objective is to get the ball over the net)
- height of release
- angle of release
- velocity of release
general motion
mix of linear and angular motion
speed
Speed = distance over time
the rate of motion (km/hr - linear) (Decrease per second or rpm - angular)
velocity
velocity = displacement over time
the rate at which an object is changing position (linear) or Rotation (angular)
acceleration - velocity
refers to the rate of change in an objects velocity
0 = constant velocity
+ = getting faster
- = getting slower
newtons first law - law of inertia
A body will remain at rest or in a uniform motion unless acted upon by an external force
greater mass therefore needs more fore
newton second law - law of acceleration
Force = mass x acceleration
refers to the force applied to an object will produce a change in motion in the direction of the force applied
more force = more acceleration
more mass = less acceleration
newtons third law - action reaction
for every action there is an equal and opposite reaction
harder you push against something (action force) the harder the reaction force will be, pushing back against us, but in the opposite direction (reaction force)
momentum
momentum = mass x velocity
refers to the amount of motion in an object
something with more momentum requires more force
large mass little velocity
smaller ass more velocity
summation of momentum
refers to the timing, coordination and sequencing of multiple body parts
allowing athletes to generate maximum force
For maximun force - summation of momentum
- use as many BODY parts as possible
- SEQUENCE - move the heavier/slower body parts first such as the legs and trunk followed by the lighter/faster body parts such as arms, wrist and fingers
- TIMING - move the next body part only when the previous body part has reached maximum velocity
- STABILIZATION - body parts must stabilize once so momentum is not lost
impulse
impulse = force x time
refers to the change in momentum of an object
to change momentum in an object, a force must be applied over a period of time
can be an increase to force or increase in time over the force applied
Torque
Torque = force x moment arm
cause an object to rotate, the amount of rotations of an object is determined by how much torque is applied and where the torque is applied
moment arm
refers to the measure from where the force is applied to the center of rotations. the GREATER the moment arm, the faster the rotation
Angular momentum
moment of inertia = mass x radius
refers to the amount of angular motion an object or body has
inertia
refers to the tendency for the body to resist a change in its state of motion
Greater inertia
more of a resistance to change state of motion = harder to move
Lower inertia
less resistance to change state of motion = easier to move
conservation of angular momentum
angular momentum = moment of inertia x angular velocity
angular motion will remain constant throughout a movement unless their is a external force acting upon the object/body
lower M of I = Increase in angular velocity
higher M of I = decrease in angular velocity
levers
refers to a rigid bar that can be made to rotate around an axis in order to exert a force on another object
levers three parts
axis (point of rotation)
Resistance (load to move)
force (point where the force is applied)
first class lever
the axis is between the force and the resistance
second class lever
the resistance is between the axis and the force
Third Class lever - Need to know
The force is between the axis and the resistance
greater range of motion
REMEMBER THAT MICLES CROSS OVER JOINTS
force arm
is the distance from the axis to the force
resistance arm
is the distance from the axis to the resistance
range of motion and speed generated can be increased by increasing the resistance arm
Mechanical Advantage
= force arm over resistance arm
is the amount by which a lever amplifies the force
mechanical advantage = force arm / resistance arm
mechanical advantage >1 will increase force
mechanical advantage <1 will increase speed and range of motion
Velocity of release - referring to projectile motion
is the most important factor when trying to maximise he horizontal distance a projectile will travel
greater force applied greater velocity release
angular of release - referring to projectile motion
is the angle the object is projectile into the air and will depend on the sport
release and landing points are the same level the best angle for maximum horizontal distance is 45 degrees
hight of release - referring to projectile motion
is the hight projectile is released compared to the hight of the landing point
Equilibrium
an object is said to be equilibrium when their are no balanced force or torque acting upon it
Balance
the ability to maintain and control equilibrium
Stability
being able to control equilibrium
center of gravity - stability
refers to the point around which the body weight is balanced, regardless of the position of the body
base of support - stability
base of support refers to the area beneath a person including the point of contact between the body and the surface
Line of gravity - stability
the direction in which gravity acts is called the line of gravity
qualitative movement analysis
is a symmetric approach to analyse performance in skills and to provide feedback to performer about the quality of those skills
observation
can be preformed by live and or recorded digitally - what can be observed
evaluation
when evaluating the performer, analyist must decide
what the problem is
what is causing it
how can it be addressed
validity
refers to the test capacity to measure what it is intended to do
reliability
refers to the ability of a test to produce consistant and repeatable results
error correction
final step of qualiative analysis
weaknesses are identified and strategies to address these are developed
