Bio Mechanical Movements Flashcards
Projectile motion
refers to movement of an object or body as it travels through the air
horizontal displacement
shortest distance from the starting point to finishing point in a line to the ground
angle, speed and height of release determine horizontal displacement
angle of release
when landing height and release height are equal the optimum angle of release is 45 degrees
eg long jumper
when landing height is above release height the optimum angle of release is greater than 45 degrees
eg basketball shot
when landing height is below release height the optimum angle of release is lower than 45 degrees
speed of release
the greater the velocity of a projectile, the greater the horizontal displacement
eg in shot put the speed across the circle ensures the shot leaves the hand at maximum velocity
height of release
a greater height of release results in a greater horizontal displacement
gravity is constantly acting upon the mass of the shot put so they should try and release it as high as possible
factors affecting flight paths
weight and gravity affect projectiles whilst they are in the air and determine whether they will have a true or distorted parabola
true parabola
projectiles with a large mass have a large weight (gravity) force and small air resistance will follow a true parabola
- longer weight arrow (pointing down)
- the longer the flight path, the more time allowed for air resistance to have an affect
distorted parabola
in projectiles with a lighter mass, air resistance will have a larger effect meaning the flight path will deviate to a distorted parabola
-the shuttlecock starts off with high velocity from force of the racquet and slows down due to the effects of air resistance
fluid mechanics
concerened with the movement in liquids and gases and how forces affect the objects in it
drag force
dynamic fluid force
acts in the opposition to motion, has a negative effect on velocity
surface drag- relates to friction between the surface of an object and the fluid environment (skin drag)
form drag- impact of fluid environment on an object
relates to streamlining- shaping a body so it can move effectively through a fluid
slipstreaming- the wind hits the front cyclist and the cyclist behind uses the air pocket behind them, so they have to exert less energy
factors affecting drag
velocity- the greater the velocity of a body through a fluid, the greater the drag so streamlining is important to reduce drag
cross sectional area of moving body- can increase or reduce drag
large CSA increases drag so cyclists crouch low over the handlebars to reduce their CSA
shape+ surface characteristics- more streamlined, aerodynamic body reduces drag
lift force
causes a body to move perpendicular to the direction of travel
achieved when different air pressures act on an object
bernoulli’s principle
where air molecules exert less pressure the faster they travel and more pressure when they travel slower
BP in projectile
angle of attack is important as it changes the flow of air around the discus, air that travels over the top of the discus has to travel a longer distance than air underneath
air above travels at higher velocity so it has a lower pressure which creates an upward lift force and allows the discus to stay in the air for longer
BP in downward
downward lift force is required by cyclists, F1 driver etc
in cycling, low streamlined body over the handlebars means that air travelling over the top of the cyclist has to travel a shorter distance than underneath
the air above travels at slower velocity, creating a higher pressure so the bike can maintain a firm grip on the track
newtons 1st law
law of inertia (tendency to resist changes in states of motion)
an object will remain at rest or uniform motion unless acted upon by an external force, that will overcome its inertia
eg ball will remain at rest until it is kicked
eg person will remain still until they contract their leg muscles and force from muscle contraction which can overcome inertia
newtons 2nd law
force= mass x acceleration
if large enough force is applied an object will
-accelerate in the direction of force
-accelerate in proportion to the amount of force applied
eg the harder a ball is kicked, the faster the ball will go/accelerate in the direction the force has been applied
newtons 3rd law
law of action and reaction
for every action there is an equal and opposite reaction
eg when a player jumps (action) a force is exerted on the ground in order to gain height, the ground exerts an equal and opposite upward force on the player
scalars
measurements are described in size or magnitude
mass, distance, speed
vectors
measurements are described in magnitude and direction
weight, acceleration, displacement, velocity, momentum
mass
amount of matter an object possesses
kg
distance
the length between the start point and finish point
metres m
speed
rate at which an object travels a specified distance
m/s
speed= distance/ time
weight
gravitational force exerted on an object
newtons N
weight= mass x GFS
velocity
rate of change of displacement
in a certain direction
ms
displacement/time
momentum
product of the mass and velocity of an object
kg m/s
displacement
total length of the path an object travels between its start and end points (400m track has 0 d)
m
acceleration
rate of change of velocity
m/s2
change in velocity/time
angular motion
movement around a fixed point or axis eg somersault
occurs when a force is applied outside the centre of mass
1st law- rotating body will continue in state of angular motion unless an external force (torque) acts upon it
2nd law- rate of change of angular momentum of a body is proportional to the force causing it and the change that takes place in the direction in which a force acts
3rd law- when a force is applied by one body to another, the second body will exert an equal and opposite force on the other body
altering angular velocity
angular momentum=moment of inertia x angular velocity
to slow down- gymnast will increase moment of inertia by extending their body or opening out
to increase speed they will decrease moment of inertia by tucking body in or bringing arms in
centre of mass
point of balance in the body, where weight is considered to act
factors affecting stability
height of centre of mass- lowering centre of mass will increase stability
position of line of gravity - should be central over the base of support to increase gravity
area of base of support- larger is more stable as there is more contact points
first class lever
fulcrum in middle, effort arrow pointing down flexion in head and neck extension at elbow MA- large ROM and moves quickly MD- can't apply much force
second class lever
resistance in middle, effort arrow up
plantarflexion at ankle
mechanical adv of generate large force
mech dis slow limited ROM
third class lever
effort in middle, arrow up
all other joints
MA- large ROM and moves quickly
MD- can’t apply much force
effort arm
shortest distance between fulcrum and application of effort
resistance arm
shortest distance between fulcrum and resistance
mechanical advantage
effort arm longer than resistance arm
lever system can move large load over short distance requiring little effort
small range of movement
mechanical disadvantage
resistance arm longer than effort arm
lever system cannot move heavy load but can move it faster
large range of movement
forces acting upon performer (linear)
internal force applied when skeletal muscles contract
external force comes from outside a body
eg gravity, friction
weight and gravity
weight = vertical force
gravitational force that the earth exerts on a body
greater mass = greater weight force pulling it down
weight= mass x acceleration
friction
friction occurs when two or more bodies are in contact with eachother
acts in opposition to motion
static friction= before object starts to move
sliding friction= when friction acts between surfaces that are moving relative to eachother
friction affected by
temperature
mass of body-larger mass means more friction
surface characteristics
air resistance
opposes motion of a body travelling through air
AR affected by
velocity- faster velocity, greater air resistance
cross sectional area- larger will be more air resistance
shape and surface characteristics- streamlined will have less air resistance
force diagrams
friction arrow points forwards
weight arrow points downwards
AR arrow points backwards
vector diagram
eg high jump
large arrow pointing up and diagonal
due to large vertical displacement
eg long jump
large arrow pointing forward
due to large horizontal component, trying to go as far as possible
impulse
force x time
time it takes a force to be applied to body
increase in impulse will result in increase in rate of change of momentum = increase in velocity
impulse can be used to increase momentum by
-increasing muscular force applied
-increasing time in which force is applied
impulse to decrease momentum
increasing the time in which forces act upon body
eg flexing hips, knees and ankles when landing extends the time of the force on the ground
force time graphs (impulse)
impulse is represented by an area under a force time graph
in 100m sprint the graph is only concerned with horizontal forces
-at start= small neg impulse and large positive impulse
net impulse is positive so sprinter is accelerating
-middle= foot makes contact with ground (neg impulse)
athlete pushes off track (pos impulse)
pos = neg impulse so moving at constant velocity
-end= higher negative impulse as they are slowing down
decelerating
