A-LEVEL PE (OCR): PAPER 1 - Biomechanics

a body continues in a STATE OF REST or UNIFORM VELOCITY unless acted upon by an EXTERNAL or UNBALANCED FORCE

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

for every ACTION FORCE applied to a body there is an EQUAL and OPPOSITE reaction force

velocity = displacement / time taken

momentum = mass x velocity

acceleration = (final velocity - initial velocity) / time taken

force = mass x acceleration

a PUSH or PULL that ALTERS that state of motion of a body

the RESISTANCE of a body to CHANGE its state of motion, whether at rest or while moving

the RATE OF CHANGE in DISPLACEMENT

the QUANTITY of MOTION possessed by a body

the RATE OF CHANGE in VELOCITY

GRAVITATIONAL PULL that the earth exerts on the body - (N)

EQUAL AND OPPOSITE FORCE in response to the action force placed upon it

the force that OPPOSES the motion of TWO SURFACES in contact

a force that OPPOSES the MOTION of a body TRAVELLING through the air

• study movement in relation to TIME AND SPACE

- white dots

• measure ground reaction forces

• test aerodynamic efficiency

- measure air resistance

the point at which a body is BALANCED in ALL DIRECTIONS

• increase mass = increase inertia

• decrease CoM

• increase BoS

• more central LoG

imaginary line that extends from the COM downwards to the FLOOR

effort - fulcrum - load

effort - load - fulcrum

load - effort - fulcrum

distance from the FULCRUM to the EFFORT

distance from the LOAD to the FULCRUM

SECOND CLASS

• effort arm is greater than the load arm

• large load / small effort

• slower

THIRD CLASS

• load arm is greater than effort arm

• small load / large effort

• faster

generated by the CONTRACTION of SKELETAL MUSCLE

100m - contract rectus femoris - extend knee - drive away from the blocks

comes from OUTSIDE the body and acts upon it

• weight

• reaction

• friction

• air resistance

• create motion

• accelerate a body

• decelerate a body

• changing the direction

• changing the shape

the football will remain at rest on the penalty spot until a force is applied to it

the greater the force applied by the footballer's foot to the ball, the greater the rate of acceleration towards the goal

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

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

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.

sum of all the forces action on a body - when all individual forces have been considered

net force = 0

two or more forces action on a body are EQUAL IN SIZE and OPPOSITE IN DIRECTION

two or more forces UNEQUAL IN SIZE and OPPOSITE IN DIRECTION = net force

weight

| reaction

mass x acceleration due to gravity

friction

| air resistance

• roughness of ground surface

• roughness of contact surface

• temperature

• size of normal reaction

increasing roughness = increased friction

increasing roughness = increasing friction

increasing temperature = increasing friction

| e.g. F1 drivers have warm up lap

increasing normal reaction = increasing friction

| e.g. shot-putters have high mass - equal / opposite high reaction force - greater friction - prevents over-rotation

• velocity

• shape

• frontal cross-sectional area

• smoothness of surface

increasing velocity = increasing air resistance

increased aerodynamic = decreasing air resistance

creation of SMOOTH AIR FLOW around an AERODYNAMIC shape to minimise air resistance

decreasing frontal cross-sectional area = decreasing air resistance

increasing smoothness = decreasing air resistance

metres per second - m/s

metres per second per second - m/s/s

kilogram metres per second - kgm/s

newtons - N

newtons - N

the extent to which an experiments produces the SAME RESULT after REPEATED TRIALS

how well a test measures what it claims to measure = accurate application and interpretation

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

a force applied through the CoM resulting in LINEAR MOTION

the total length covered from start to finish (m)

the shortest straight-line route from start to finish (m)

the rate of change in DISTANCE (m/s)

a visual representation of the DISTANCE travelled plotted AGAINST the TIME taken

a visual representation of the SPEED OF MOTION plotted AGAINST the TIME taken

a visual representation of the VELOCITY OF MOTION plotted against the TIME taken

movement of a body or part of a body in a CIRCULAR PATH about an AXIS OF ROTATION

a force applied OUTSIDE the CoM, resulting in ANGULAR MOTION

a MEASURE of the TURNING force applied to a body

skeleton bob at top speed

gymnastic somersault

from head to toe (through the CoM)

from left to right (through the CoM)

from front to back (through the CoM)

flat spin on ice

somersault

cartwheel

the rate of change in ANGULAR DISPLACEMENT (radians per second)

the RESISTANCE of a body to change its state of ANGULAR MOTION or ROTATION

mass x distance from axis

the QUANTITY of ANGULAR MOTION possessed by a body