biomechanics yr 1 Flashcards
centre of mass
the point at which the body is balanced in all directions
Fosbury flop technique in relation to COM
-uses j curve to allow greater velocity in approach
-plants outside foot to allow inside foot to lift along with the arms at take off to raise the COM as high as possible
-full extension of the spine too rotate arounds the bar moving the COM outside the body and below the bar
-only one section of body around the bar at one time
-because the COM is below the bar the Fosbury flop requires less force at take off to clear the same heights as earlier techniques
4 factors that affect stability
mass of body - the greater the mass of there body the greater its inertia and therefore stability
height of the COM - lower the COM the greater the stability
Base of support - greater the size of the base of support the greater the stability as you can increase surface area or have more points of contact on the floor
line of gravity - an imaginary line which extends from the COM down to the floor, the more central the line is to the base of support the more stability
example of runner maximising stability
crouched position gives a low COM
base of support large with 5 points of contact
line of gravity within the base of support and sprinter has a high mass due to muscle mass
stability
the ability of a body to resist motion and remain at rest
mechanical advantage
second class lever systems where the effort arm is greater than the load arm
mechanical disavadntage
third class lever system where the load arm is greater than the effort arm
lever systems
co-ordination of our bones and muscles primarily to create human movement
biomechanics
the study of human movement and the effect of force and motion on sport performance
Newtons 1 law
the body remains at rest or uniformed velocity until acted on by and external or unbalanced force
inertia
the resistance of a body top change its state of motion whether at rest or moving
newtons second law
a body rate of change in momentum is proportional to the size of the force applied and acts in the same direction as the force applied
newtons second law
a body rate of change in momentum is proportional to the size of the force applied and acts in the same direction as the force applied
momentum
the quantity of motion possessed by a moving body
newton 3 law
for every action force applied to the body there is an equal and opposite reaction force
velocity def and eq
the rate of change in displacement
displacement / time taken
momentum eq
mass x velocity
acceleration def and eq
rate of change in velocity
final velocity - initial velocity / time taken
force
push or pull that alters the state of motion on a body
f=ma
5 effects of force
create motion
accelerate a body
decelerate a body
change the direction of the body
change the shape of a body
weight def and eq
the gravitational pull the earth exerts on the body
mass x acceleration due to gravity
2 vertical forces
weight and reaction
4 factors that affect friction
roughness of the ground surface - by increasing roughness friction is increased
roughness for contact surface - by increased roughness of contact surface friction increases
temperature - increased temp of ground leads to more contact surface friction
size of normal reaction - increased normal reaction force leads to increased friction e.g shot put have high mass therefore reaction force is high allowing for greater friction in the turning circle
4 factors that affect AR
velocity- by increasing velocity AR increases
Shape- more aerodynamic shape the less AR
Frontal CSA- by decreasing the Frontal cross sectional area Ar decreases
smoothness of surface- increasing the smoothness of the surface air resistance decreases
limb kinematics
the study of movement in relation to time and space
3D analysis records an athlete performing a sporting action and allows joint and limb efficiency to be evaluated
pros and cons of limb kinematics
+immediate data
+highly accurate
+used by coaches to adjust technique
- dependant on correct placement of body markers
-does not cater for individual differences
- expensive
-limited to lab conditions
force plates
measures ground reaction force
assess the size and direction force acting on the athlete
Used for gait analysis
rectangular plate with built in force transducers usually sunk into the ground to become part of the floor and electrical output proportional to the force applied is displayed
pros and cons of force plates
+immediate
+accurate
+reliable
-expensive
-specialist
-lab conditions
Wind tunnels
objects are tested for aerodynamic efficiency
Object is placed inside the wind tunnel with instruments to measure the forces produced by the air against the surface
pros and cons of wind tunnels
+ tight control over environmental variables
+ accurate measurements of AR
+ quick results
- specialised facilities
-expensive
-complex analysis needed from professionals
