BIOMECHANICS Flashcards
Fluid mechanics
study of fluids and how forces affect them
drag force
Resistance force caused by motion of moving body through fluid slowing it down.
Acts in opposite direction of motion.
2 different types of drag
- surface drag
- form drag
surface drag
friction between the surface of an object + fluid environment. swimmers were specialised clothing to reduce
form drag
impact of fluid environment on the object. Forces affecting the leading edge of an object increase form drag and forces affecting the trailing edge reduce drag. Related to streamlining.
streamlining
shaping a body so it can move effectively and quickly through a fluid
factors increasing and reducing drag
- velocity of moving body
- crosssectional area of moving body
- shape and surface characteristics of moving body
drag is produced from …
air resistance and friction
example of surface drag
swimmers wear specialised clothing to reduce surface drag
example of form drag
swimmer has to created straightest form as they move through the water and cyclist will use others riders slipstream. 2nd cyclist can save up to 30% more energy
how velocity of moving body affects drag
the greater the velocity the greater the drag force. so streamlining is important.
how cross sectional area of moving body affects drag
large cross-sectional area increases drag. In Tour de France reducing their cross sectional area is vital to reduce drag through crouching over the handlebars rather than sitting upright.
how shape and surface of moving body affect drags
regularly making drag resistant clothing to achieve gains in speed. In cycling clothing with ridges and aerodynamic helmet have been designed to reduce the effects of drag. Badminton shuttlecock has a larger drag force from air resistance.
Bernoulli’s principle definition
where air molecules exert less pressure the faster they travel and more pressure when slower.
lift force definition
causes a body to move perpendicular to direction of travel eg. discuss allowing it to stay in air longer
what causes lift
when different air pressures act on an object. Air that travel faster has a lower pressure.
angle of attack definition
the tilt of a projectile relative to airflow
why is angle of attack important
it changes the flow of air around the discuss so that air travels over the top of the discuss has to travel a longer distance than air underneath. This results in a faster velocity creating a lower pressure. The lower pressure above the discuss creates an upward lift force allowing the discuss to stay in the air for longer
what happens if angle of attack is too large
lift is reduced and drag increases causing discuss to stall.
what is the optimum angle of attack for a discuss
25-40 degrees
formula 1 downward lift force example
formula 1 car, cyclists and speed skiers. In formula 1 the air travels over car at a shorter distance due to angle of spoiler. So air above car travels at slower velocity with more pressure creating a downward lift force so tyres maintain a firm grip on track.
cyclist downward lift force
low streamlined body over handlebars means air travels over top of cyclist and travels a shorter distance than air underneath. Air travels at a slower velocity at a higher pressure creating a downwards lift force allowing tyres of bike to maintain firm grip on track.
Drag force has a negative effect on…
Velocity
newtons first law
law of inertia. a force is required to change state of motion
newtons second law
law of acceleration. The magnitude and direction of force determines the magnitude and direction of acceleration.
newtons third law
law of action and reaction. for every force there is an equal and opposite reaction force.
factors affecting stability
- height of centre of mass
- area of base of support
- position of line of gravity
- mass of performer
mechanical advantage 1st class and 3rd class
large range of movement and any resistance can be moved quickly
mechanical disadvantage 1st class and 3rd class
cant apply much force to an object
mechanical advantage 2nd class
generate larger forces has to lift whole body weight
mechanical disadvantage 2nd class
slow with limited range of movement
impulse
time it takes a force to be applied to an object or body
factors affecting horizontal displacement
- height of release
- angle of release
- speed of release
angle of release when landing height is above release height
more 45 degrees
angle of release when landing height is below release height
less 45 degrees
speed of release
greater speed of release the greater the horizontal displacement
height of release
greater release height increases horizontal displacement as force of gravity is constantly acting on object
what two forces affect projectiles
weight/gravity and air resistance
parabola
uniform curve that is symettrical at highest point
