1.3a biomechanics Flashcards
define newtons 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 KINEMATICS ?
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
