biomechanical principles Flashcards
what is newtons first law
(inertia)
a body will remain in a state of rest or uniform motion unless acted on by an external or unbalanced force
what is newtons second law
(acceleration)
a bodys rate of change in momentum is proportional to the size of the force applied and acts in the same direction of the force applied
what is newtons third law
(reaction)
for every action force applied to a body there is an equal and opposite reaction force
what is a force
a push or pull that alters the state of motion of a body. All forces are measured in Newtons
how does forces affect bodies
-create motion
-accelerate
-decelerate
-change direction
-change shape
what is a net force
the sum of all forces acting on a body are considered. it shows the resultant force. We consider vertical and horizontal forces separately.
vertical=weight and reaction
horizontal=friction and wind resistance
what are the forces if the net=0
forces are balanced
what re the forces if the net is not 0
forces are unbalanced
factors affecting friction
-roughness of ground surface
-roughness of contact surface
-temperature
-size of reaction force
factors affecting air resistance
-velocity
-shape
-frontal cross-sectional area
-smoothness of surface
example of a vertical force
-weight
-reaction
example of a horizontal force
-friction
what is the equation for weight
weight = mass x 9.807
what is the equation for velocity
displacement / time taken
equation for momentum
mass x velocity
equation for acceleration
final velocity - initial velocity / time taken
centre of mass definition
the point of which a body is balanced in all directions
what are the affecting factors of centre of mass
-height of centre of mass
-mass of the body
-size of the base of support
-the line of gravity
-number of points of contact
what is mechanical advantage
less effort is required to move a large load
what is mechanical disadvantage
a large effort is required to move a small load
does class one levers have mechanical advantage or disadvantage
they can have mechanical advantage or disadvantage as it depends on the position of the fulcrum which determines the length of the load and effort arm
does class two levers have mechanical advantage or disadvantage and why
always have mechanical advantage as the effort arm is always bigger than the load arm
does class three levers have mechanical advantage or disadvantage and why
always have mechanical disadvantage as the effort arm is always shorter than the load arm
equation for mechanical advantage
load/effort
what is limb kinematics
the study of movement of limbs in space, and time taken to carry out the movements. it includes the study of gait
how does limb kinematics work
reflective markers are placed on the performers body landmarks and they are filmed using multiple video cameras. the data is then transferred into digital form for analysis
is limb kinematics reliable and why
not reliable as there are many factors that can affect the results each time
what are advantages of limb kinematics
-information is readily available
-the coach can use the information to make changes in technique
-can examine the effect of movements causing injury
-investigates technique effectiveness
disadvantages of limb kinematics
-expensive equipment
-results do not take into account individuals differences
-lab conditions are unrealistic
what does limb kinematics assess
bone geometry, displacement, velocity and acceleration in multiple planes
is limb kinematics valid
yes as long as it is done correctly and the position of the markers are precise
what are force plates
measuring instruments that measure the ground reaction force generated by a body standing or moving
what law does force plates use
newtons 3rd law of motion
what are the uses of force plates
prevents injury and increases performance
what are advantages of force plates
-optimises performance
-minimises injury
-accurate
-enhances training
-reliable
-valid
what are the disadvantages of force plates
-expensive
-hard to use
-cant tell where the force is coming from
what are wind tunnels
tubular passage used to study the effects of air travelling over, under and through solid objects
what are advantages of wind tunnels
-marginal gains to reduce air resistance and increase stream line to increase speed
-controls cross winds
-improves the flow of air around an object, reduces drag, increases lift and streamlining
what are disadvantages of wind tunnels
-expensive
-complex
-need specialised equipment
what does coloured smoke do in wind tunnels
used to see how the air interacts with an object
