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Biomechanics - Coggle Diagram
Biomechanics
LINEAR KINETIC & KINEMATICS
Linear Kinetics
(week 9)
typical factors in kinetic analysis
Mass
scalar quantity
quantity of matter composing an object
mass depends on the density and volume of the object
an object's mass is constant regardless of where it is
SI unit: kg (kilogram)
mass = density x voulume
Volume
scalar quantity
measure of the amount of space occupied by a body
SI unit: m^3
Force
magnitude
value in N (newtons)
direction
usually in degree or radians
point of application
line of action
push or pull
Torque
Linear Momentum
(A quantity of motion; may be increased or decreased by increasing or decreasing either the mass or the velocity)
mass x velocity
Principle of Conservation m1v1=m2v2
Newton's First Law of Motion
Law of Inertia
a body will remain at its state of rest or constant velocity unless acted on by an external force that changes the state
inertia of an object is proportional to its mass
the greater the law of inertia, the more difficult it is to change its motion
to alter an object's motion, there must be an unbalanced force applied to overcome its inertia
Newton's Second Law of Motion
Law of Acceleration
a force applied to a body causes an acceleration of a magnitude proportional to the force, in the direction of the force and inversely proportional to the body mass
F (N) = m (KG) x a (m/s^2)
Newton's Third Law of Motion
Law of Gravitation
for every force that is exerted by one body on another, there will be an equal and opposite force exerted by the second body on the first
Linear Kinematics
(week 9)
Linear motion
(Translation)
Distance
scalar quatity
SI unit: m (metre)
magnitude only
Displacement
Positive when moving towards the right of x-axis
vector quantity
SI unit: m (metre)
magnitude and direction
Speed
Scalar quantity
SI unit: m/s
magnitude only
distance travelled divided by time taken
Velocity
vector quantity
magnitude and direction
SI unit: m/s
displacement divided by time taken
rate of change of displacement
Acceleration
acceleration due to gravity, g = 9.81 m/s^2
rate of change of velocity
SI unit: m/s^2
running 100m along a straight track
Motion in which all point on an object moves through the
same distance
, in the
same direction
, at the
same time
curvilinear motion
travelling along a curved path
rectilinear motion
driving along a straight road
walking down a straight path
straight line motion
General
translation and rotation combined
riding a bicycle
Angular
(Rotation)
rotation of a body about a fixed point or line in space
all points move through same angle, direction and time
moving about a high bar in gymnastics
Projectile Motion
air resistance
during flight
release height
relative to height of landing
angle
at instance of release
speed
at instance of release
ball rotation
during flight
ANGULAR KINETICS & KINEMATICS (week 10)
Angular Kinematics
Angular distance
Angular displacement
Vector quantity: has direction and magnitude. + when counter clockwise, - when clockwise. Radian or degree
Scalar: only has magnitude
Angular Speed (rad/s)
Angular Velocity (rad/s)
Vector quantity. Will be + vector when turning counter-clockwise, - clockwise
Greater the length of rotating lever, the greater the linear displacement and velocity at the distal end of the lever
velocity= radius x angular velocity
Speed and ROM come at expense of force applied
General motion
Linear motion+ Angular motion
Vgeneral= Vlinear +Vangular
Vangular= r x angular velocity
Angular Kinetics
Force that cause motion
Torque
Force x ⊥distance (moment arm)
1st Class Lever
Applied force & Resistance are on opposite sides of axis.
E.g scissors
2nd Class Lever
Applied force & Resistance on same side of axis.
Resistance closer to axis than Applied force.
E.g. wheelbarrow
3rd Class Lever
Force & Resistance on same side of axis
Applied force closer to axis than Resistance.
Most anatomical levers are third class levers
E.g. paddle used in rowing
Moment of inertia
(Rotational Inertia )
-Mass of Object
-Mass Distribution to axis of rotation
Bent leg reduces rotational inertia
Angular momentum
Increase mass, velocity and distance from axis of rotation to increase angular momentum
Angular momentum
Increase mass of an object
Shift mass as far from axis of rotation
Increase angular velocity of whatever is rotated
Ground Reaction Force (Week 11)
Newton 3rd Law (Gravitation)
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
Impulse Momentum
Impulse, Ft = m(vf – vi) [Ns]
Impulse = Force x Time
If increase velocity (Speed), Force, If move with great momentum, the impulse will be greater
Landing
Bending knee when landing increase the time this decreasing force acting on body which avoid injury
Take off
Leaning back on the back leg, increase distance, time, more impluse thus higher flight
Force = Mass x Acceleration
(Newton 2nd Law)
Momentum = Mass x Velocity
Velcoity = Displacement / Time
Kinetic Chain Theory
A series of adjacent segments in which movements at one joint cause a series of reactions in other joints.
Joints and segments in the body have an effect on one another during movement.
When one is in motion, it creates a chain of events that affects the movement of neighboring joints and segments.
Closed Chain
Training end is fixed
Push Up, Chin Up, Squat
Open Chain
Training End is moving
Running, Swimming
Sequential Movements
Preparatory Phase
Lengthen the appropriate muscles so they will be in position to generate greater force & momentum
Take advantage of impulse-momentum relationship
Eccentric contraction of agonist muscles for the force phase ( stretch-shortening cycle)
Movementt Phase
It is the phase in which the summation of forces is generated directly to the external object
Concentric contraction of agonist muscles
Follow- through Phase
Known as deceleration phase, the velocity of the body segment progressively decreases
Eccentric contraction of antagonist muscles
The shorter the follow-through, the more forcefully the muscles have to contract
