PAPER 1 - Biomechanics Flashcards
Define Newton’s First law of motion : INERTIA
a body continues in a STATE OF REST or UNIFORM VELOCITY unless acted upon by an EXTERNAL or UNBALANCED FORCE
Define Newton’s Second law of motion : ACCELERATION
a body’s RATE OF CHANGE in MOMENTUM is PROPORTIONAL to the SIZE of the FORCE applied and acts in the SAME DIRECTION as the force applied
Define Newton’s Third law of motion : REACTION
for every ACTION FORCE applied to a body there is an EQUAL and OPPOSITE reaction force
What is the equation for VELOCITY ?
velocity = displacement / time taken
What is the equation for MOMENTUM ?
momentum = mass x velocity
What is the equation for ACCELERATION ?
acceleration = (final velocity - initial velocity) / time taken
What is the equation for FORCE ?
force = mass x acceleration
Define FORCE
a PUSH or PULL that ALTERS that state of motion of a body
Define INTERTIA
the RESISTANCE of a body to CHANGE its state of motion, whether at rest or while moving
Define VELOCITY
the RATE OF CHANGE in DISPLACEMENT
Define MOMENTUM
the QUANTITY of MOTION possessed by a body
Define ACCELERATION
the RATE OF CHANGE in VELOCITY
Define WEIGHT
GRAVITATIONAL PULL that the earth exerts on the body - (N)
Define REACTION
EQUAL AND OPPOSITE FORCE in response to the action force placed upon it
Define FRICTION
the force that OPPOSES the motion of TWO SURFACES in contact
Define AIR RESISTANCE
a force that OPPOSES the MOTION of a body TRAVELLING through the air
What are LIMB KINETICS ?
- study movement in relation to TIME AND SPACE
- white dots
What are FORCE PLATES ?
- measure ground reaction forces
What are WIND TUNNELS ?
- test aerodynamic efficiency
- measure air resistance
Define CENTRE OF MASS
the point at which a body is BALANCED in ALL DIRECTIONS
How do you increase stability ?
- increase mass = increase inertia
- decrease CoM
- increase BoS
- more central LoG
Define LINE OF GRAVITY
imaginary line that extends from the COM downwards to the FLOOR
What is a FIRST CLASS lever ?
effort - fulcrum - load
What is a SECOND CLASS lever ?
effort - load - fulcrum
What is a THIRD CLASS lever ?
load - effort - fulcrum
What is the EFFORT ARM ?
distance from the FULCRUM to the EFFORT
What is the LOAD ARM ?
distance from the LOAD to the FULCRUM
What is MECHANICAL ADVANTAGE ?
SECOND CLASS
- effort arm is greater than the load arm
- large load / small effort
- slower
What is MECHANICAL DISADVANTAGE ?
THIRD CLASS
- load arm is greater than effort arm
- small load / large effort
- faster
What is an INTERNAL FORCE ?
generated by the CONTRACTION of SKELETAL MUSCLE
INTERNAL FORCE : EXAMPLE
100m - contract rectus femoris - extend knee - drive away from the blocks
What is an EXTERNAL FORCE ?
comes from OUTSIDE the body and acts upon it
What are the 4 examples of EXTERNAL FORCES ?
- weight
- reaction
- friction
- air resistance
What are the 5 effects of FORCE ?
- create motion
- accelerate a body
- decelerate a body
- changing the direction
- changing the shape
Using a football penalty as an example: how does force (1) CREATE MOTION ?
the football will remain at rest on the penalty spot until a force is applied to it
Using a football penalty as an example: how does force (2) ACCELERATE A BODY ?
the greater the force applied by the footballer’s foot to the ball, the greater the rate of acceleration towards the goal
Using a football penalty as an example: how does force (3) DECELERATE A BODY ?
as the ball moves through the air towards the goal, the force of AIR RESISTANCE will act in the OPPOSITE direction and slow it down
Using a football penalty as an example: how does force (4) CHANGE THE DIRECTION OF A BODY ?
as the goalkeeper dives to save a high corner shot, he will apply force from his HANDS to the BALL, changing it’s direction pushing it AWAY from the goal
Using a football penalty as an example: how does force (5) CHANGE THE SHAPE OF A BODY ?
if the goalkeeper fails to make the save, the force of the ball coming into contact with the NET will change the shape of the net.
What is NET FORCE ? (resultant force)
sum of all the forces action on a body - when all individual forces have been considered
What is the net force when forces are BALANCED ?
net force = 0
What are BALANCED FORCES ?
two or more forces action on a body are EQUAL IN SIZE and OPPOSITE IN DIRECTION
What are UNBALANCED FORCES ?
two or more forces UNEQUAL IN SIZE and OPPOSITE IN DIRECTION = net force
What are the 2 VERTICAL FORCES ?
weight
reaction
What is the equation for WEIGHT ?
mass x acceleration due to gravity
What are the 2 HORIZONTAL FORCES ?
friction
air resistance
What 4 factors affect FRICTION ?
- roughness of ground surface
- roughness of contact surface
- temperature
- size of normal reaction
How does (1) ROUGHNESS OF GROUND SURFACE affect friction ?
increasing roughness = increased friction
How does (2) ROUGHNESS OF CONTACT SURFACE affect friction ?
increasing roughness = increasing friction
How does (3) TEMPERATURE affect friction ?
increasing temperature = increasing friction
e.g. F1 drivers have warm up lap
How does (4) SIZE OF NORMAL REACTION affect friction ?
increasing normal reaction = increasing friction
e.g. shot-putters have high mass - equal / opposite high reaction force - greater friction - prevents over-rotation
What 4 factors is AIR RESISTANCE affected by ?
- velocity
- shape
- frontal cross-sectional area
- smoothness of surface
How does (1) VELOCITY affect air resistance ?
increasing velocity = increasing air resistance
How does (2) SHAPE affect air resistance ?
increased aerodynamic = decreasing air resistance
What is STREAMLINING ?
creation of SMOOTH AIR FLOW around an AERODYNAMIC shape to minimise air resistance
How does (3) FRONTAL CROSS-SECTIONAL AREA affect air resistance ?
decreasing frontal cross-sectional area = decreasing air resistance
How does (4) SMOOTHNESS OF SURFACE affect air resistance ?
increasing smoothness = decreasing air resistance
What are the units for velocity ?
metres per second - m/s
What are the units for acceleration ?
metres per second per second - m/s/s
What are the units for momentum ?
kilogram metres per second - kgm/s
What are the units for force ?
newtons - N
What are the units for weight ?
newtons - N
What is RELIABILITY ?
the extent to which an experiments produces the SAME RESULT after REPEATED TRIALS
What is VALIDITY ?
how well a test measures what it claims to measure = accurate application and interpretation
What is LINEAR MOTION ?
movement of a body in a STRAIGHT or CURVED line, where all parts move the SAME DISTANCE, in the SAME DIRECTION over the SAME TIME
What is DIRECT FORCE ?
a force applied through the CoM resulting in LINEAR MOTION