OCR A Level Physical Education A 7875
OCR Examinations
A Level Physical Education
A 7875
Module 2565 : Option B1
part 2
Biomechanical Analysis of Human Movement
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Module 2565 B1.2.1
INDEX
Index
OCR A Level Physical Education A 7875
3
4
5
6
7
8
9
- IMPULSE
- IMPULSE - FOLLOW THROUGH
- IMPULSE - FORCE TIME GRAPHS
- IMPULSE - CALCULATION OF VELOCITY OF STRUCK BALL
- WORK AND ENERGY - WORK
- WORK AND ENERGY - ENERGY
- APPLICATIONS OF WORK FORMULA
WORK FORMULA APPLIED TO THROWS
10 - APPLICATIONS OF WORK FORMULA
11 - APPLICATIONS OF WORK FORMULA
BOB SLEIGH START
12 - POWER
13 - PROJECTILES - PROJECTILES AND YOUR PPP
14 - RELEASE
15 - FLIGHT
16 - FLIGHT - WEIGHT
17 - FLIGHT - RELATIVE SIZE OF FORCES
18 - FLIGHT - LARGE AIR RESISTANCE
19 - FLIGHT - THE BERNOULLI EFFECT
20 - FLIGHT AND LIFT - LIFT FORCES
21 - SPIN - THE MAGNUS EFFECT
22 - BOUNCING BALLS WITH SPIN
23 - CENTRE OF MASS - WHERE IS THE CENTRE OF MASS?
24 - BALANCE and TOPPLING
25 - CENTRE OF MASS - GENERATION OF ROTATION
FORCE ACTING AT TAKE-OFF THROUGH CoM
26 - CENTRE OF MASS - GENERATION OF ROTATION
FORCE ACTING AT TAKE-OFF NOT THROUGH CoM
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27 - LEVERS
28 - CLASSIFICATION OF LEVERS
29 - EFFICIENCY OF LEVERS
30 - MOMENT OF FORCE - TORQUE - PRINCIPLE of MOMENTS
31 - CALCULATION OF EFFORT IN MUSCLE
FORCE IN TRICEPS MUSCLE a worked example
32 - PRINCIPAL AXES OF ROTATION - BODY PLANES & AXES
33 - BODY PLANES FOR MOVEMENT
34 - ANGULAR MOTION - TORQUE
MOMENT OF FORCE / TORQUE / COUPLE
35 - ANGULAR MOTION - ANALOGUES OF NEWTON’s LAWS
36 - ANGLE - ANGULAR DISPLACEMENT
37 - ANGULAR VELOCITY
38 - ANGULAR ACCELERATION
39 - MOMENT OF INERTIA
40 - MOMENT OF INERTIA
41 - MOMENT OF INERTIA - The SPRINTER’S LEG
42 - CONSERVATION OF ANGULAR MOMENTUM
ANGULAR MOMENTUM
CONSERVATION of ANGULAR MOMENTUM
43 - CONSERVATION OF ANGULAR MOMENTUM - EXAMPLES
THE SPINNING SKATER / THE TUMBLING GYMNAST
44 - CONSERVATION OF ANGULAR MOMENTUM - EXAMPLES
DANCER - SPIN JUMP / THE SLALOM
45 - CONSERVATION OF ANGULAR MOMENTUM - EXAMPLES
THE LONG JUMPER - BEFORE TAKE-OFF
Module 2565 B1.2.2
OCR A Level Physical Education A 7875
Impulse
IMPULSE
IMPULSE
• another concept derived from Newton's second law
•
•
•
impulse = total change of momentum
= force x time
useful when large forces are applied for short times
•
examples of use of impulse :
– fielder catching a hard cricket ball
– bat, racquet, stick, golf club striking a ball
– footballer kicking a ball
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Module 2565 B1.2.3
OCR A Level Physical Education A 7875
Impulse
IMPULSE
IMPULSE
• = force x time
•
when a bat strikes a ball, a large force is applied to the ball for a
short time
•
follow through when striking a ball :
– increases time of contact
– therefore increases impulse
– therefore increases final momentum (and hence the speed) of
struck ball
•
the
–
–
–
–
turn in the discus throw
increases the time over which force is applied
therefore increases the impulse
and increases the final momentum of the discus
hence increases the speed of release and the distance thrown
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Module 2565 B1.2.4
OCR A Level Physical Education A 7875
Impulse
IMPULSE
FORCE TIME GRAPHS
• the area under this graph is the impulse
•
•
the graph below represents the force time graph
for the force between foot and ground during a
foot strike when sprinting
the bigger the area
– the bigger the impulse
– and the greater the change of momentum of
the runner
– the greater the acceleration
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Module 2565 B1.2.5
OCR A Level Physical Education A 7875
Impulse
IMPULSE
CALCULATION OF VELOCITY OF STRUCK BALL
• estimate the area under the force time graph
• this is the impulse, I = Ft
• and I = change of momentum of the ball, = D mv
•
•
•
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divide by the mass of the ball gives you the change
in velocity of the ball, = D v
subtract incoming velocity (= - u) (remember to
make it negative if ball travels towards the bat)
final velocity v = D v - (- u)
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Module 2565 B1.2.6
OCR A Level Physical Education A 7875
Work and Power
WORK AND ENERGY
WORK
• is the scientific form of mechanical energy
• work = force x distance moved in direction of force
• unit the joule J
•
example :
– work done on a cycle ergometer
– work = force x distance moved
– force = weight hung from wheel in Newtons (the
weight will be 10 N per kg mass)
– distance = circumference of wheel x number of
revolutions of wheel
– answer in joules
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Module 2565 B1.2.7
OCR A Level Physical Education A 7875
Work and Power
WORK AND ENERGY
ENERGY
• work is the same thing as energy
• work is the energy used for exerting forces (i.e.
mechanical energy)
•
energy for physical activity comes from chemical fuel
foods
•
the chemical reaction which converts this energy into
work is a complex biochemical / physiological process
involving ATP, glucose, and oxygen
•
kinetic energy (KE) is energy due to movement
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Module 2565 B1.2.8
OCR A Level Physical Education A 7875
Work and Power
APPLICATIONS OF WORK FORMULA
WORK FORMULA APPLIED TO THROWS
• work = force x distance
• this work is provided by energy converted from food fuel in the
body
•
the throwing action converts this work into kinetic energy
(KE = energy of movement) of the thrown object
•
therefore to maximise this KE, the thrower must maximise :
– the force applied to the implement throughout the throw
– by doing strength training
– and the distance over which the force is applied
– by learning the technique of the throw
– and doing flexibility training
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Module 2565 B1.2.9
OCR A Level Physical Education A 7875
Work and Power
APPLICATIONS OF WORK FORMULA
FORCE DISTANCE GRAPH
• work = force x distance
• the area under the force time graph is equal to the work done
by the force over the distance
•
in the case of the thrower this work is converted into kinetic
energy (KE)
•
the formula for KE = 1 m v2
2
this formula enables you to work out the release velocity of
the thrown implement
•
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Module 2565 B1.2.10
OCR A Level Physical Education A 7875
Work and Power
APPLICATIONS OF WORK FORMULA
BOB SLEIGH START
• the work formula is relevant
• because force is applied over a distance
•
the work done by the pushers is
converted into kinetic energy of the
sleigh + bobsleighmen
•
work = force x distance
•
therefore maximum possible force
has to be exerted over the maximum
possible distance during the shove
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Module 2565 B1.2.11
OCR A Level Physical Education A 7875
Work and Power
POWER
POWER
•
= rate of doing work
= rate of using energy
= work done or energy used
time taken
• unit the watt W
•
•
power = force x speed (another definition)
a powerful sportsperson can apply force at speed
•
example : to find a person's power running
upstairs
– he exerts a force = weight of person
– through a distance = height moved
– work = weight (N) x height (m) (ans J)
= potential energy gained by person
– power =
work
(ans W)
time taken to run upstairs
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Module 2565 B1.2.12
OCR A Level Physical Education A 7875
Projectile Motion
PROJECTILES
PROJECTILES
• the motion of objects in flight
– human bodies
– shot / discus / javelin /
hammer
– soccer / rugby / cricket
tennis / golf balls
PROJECTILES AND YOUR PPP
• you should include an analysis of
any relevant projectile motion in
your chosen sports in your PPP
•
•
is governed by the forces acting
– weight
– air resistance
– Magnus effect
– aerodynamic lift
•
and the direction of motion
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include analysis of
– release conditions
– forces likely to be acting
– spin
– flight pattern or path
Module 2565 B1.2.13
OCR A Level Physical Education A 7875
Projectile Motion
RELEASE
angle of
release
height of
release
DISTANCE
TRAVELLED BY
PROJECTILE
speed of
release
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Module 2565 B1.2.14
OCR A Level Physical Education A 7875
Projectile Motion
FLIGHT
air
resistance
weight
FORCES ACTING
Magnus
aerodynamic
lift
effect
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Module 2565 B1.2.15
OCR A Level Physical Education A 7875
Projectile Motion
FLIGHT
WEIGHT
• weight will always act on a body in flight
• the amount to which weight is a predominant force acting governs the
shape of the flight path
• if weight were the only force acting then the shape of the flight path
would be a parabola
• some flight paths are similar to this
– shot / hammer
– human body in jumps / tumbles / dives
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Module 2565 B1.2.16
OCR A Level Physical Education A 7875
Projectile Motion
FLIGHT
RELATIVE SIZE OF FORCES
• the faster the projectile travels the greater
will be air resistance
•
aerodynamic lift applies to
– thrown objects with a wing shape profile
– javelin / discus / rugby ball / American
football / frisbee
•
the Magnus effect applies to spinning
balls
•
if the shapes of the flight path differ from a
parabola then some combination of these
forces must be relatively large compared
with the weight
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Module 2565 B1.2.17
OCR A Level Physical Education A 7875
Projectile Motion
FLIGHT
LARGE AIR RESISTANCE
• example :
– badminton shuttle struck
hard
– the air resistance is very large
compared with the weight
– the resultant force is very close
to the air resistance
•
the shuttle would slow down
rapidly over the first part of the
flight
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•
later in the flight of a badminton
shuttle :
– now the air resistance is much
less
– and comparable with the weight
•
This pattern of the resultant force
changing markedly during the flight
predicts a markedly asymmetric path
•
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Module 2565 B1.2.18
OCR A Level Physical Education A 7875
Projectile Motion
FLIGHT - THE BERNOULLI EFFECT
BERNOULLI EFFECT
• is the effect that enables aerofoils
to fly
•
•
•
•
•
as layers of air flow past the wing
the layers under the wing flow
further and faster than those
over the top of the wing
caused by reduction in pressure
on a surface across which a fluid
moves
the greater the speed, the bigger
the pressure difference, the greater
the force
this
–
–
–
effect is used in sport :
inverted wings on racing cars
create down-force
which then increases friction for
cornering
•
•
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this causes reduced pressure
under the wing
and hence a downward force
Module 2565 B1.2.19
OCR A Level Physical Education A 7875
Projectile Motion
FLIGHT AND LIFT
LIFT FORCES
• these forces are caused by bulk
displacement of fluid and are similar
to air resistance
• a wing shaped object moves through
the air
– discus
– ski jumper
•
•
•
as it moves forward and falls through
the air, it pushes aside the air
creating a higher pressure underneath
the object
and a lower pressure over the top of the
object
•
and creates a lift force
•
this force is similar to the force which
enables a stone to skip over the surface
of water
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Module 2565 B1.2.20
OCR A Level Physical Education A 7875
Projectile Motion
SPIN
THE MAGNUS EFFECT
• this is the Bernoulli effect applied to
spinning (swerving) balls
• the spin takes more layers of air the
long way round the ball
• this means that the air travels faster
round this part of the ball
•
•
therefore there is a reduction in
pressure on this side of the ball
this causes the Magnus effect force
as shown
•
the direction of swerve of spinning
ball is therefore in the same sense as
the direction of spin
•
•
•
•
back spin - soar
top spin - dip
side spin - slice and hook
soccer free-kicks - swerving
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Module 2565 B1.2.21
OCR A Level Physical Education A 7875
Projectile Motion
BOUNCING BALLS WITH SPIN
BOUNCING BALLS
• as a ball bounces there is friction
between the lowest point of the ball
and the ground
•
if the ball is spinning, this friction can
be increased or reduced
•
a ball with back spin will have
increased backwards friction with the
ground which will cause the ball to
bounce backwards form its normal
path
•
a ball with top spin will have friction
driving forwards on the ball - making
the ball travel forward of its normal
path
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Module 2565 B1.2.22
OCR A Level Physical Education A 7875
Centre of Mass
CENTRE OF MASS
CENTRE of MASS (CoM)
• this is the single point in a body which represents all the
spread out mass of a body
•
the weight acts at the CoM since gravity acts on mass to
produce weight
WHERE IS THE CENTRE OF MASS?
• position of centre of mass depends
on shape of body
• this is how the high jumper can have
his CoM pass under the bar
• but he could still clear the bar
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Module 2565 B1.2.23
OCR A Level Physical Education A 7875
Centre of Mass
BALANCE and TOPPLING
BALANCE
• to keep on balance the CoM must
be over the base of support
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TOPPLING
• the CoM must be over the base of support
if a person is to be on balance
•
toppling would be caused by the weight
acting at the CoM creating a moment about
the near edge of the base of support
•
this can be used by divers or gymnasts to
initiate a controlled spinning (twisting) fall
and lead into somersaults or twists
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Module 2565 B1.2.24
OCR A Level Physical Education A 7875
Centre of Mass
CENTRE OF MASS - GENERATION OF ROTATION
FORCE ACTING AT TAKE-OFF THROUGH CoM
•
the line of action of a force on a jumper
before take-off determines whether or not
he rotates in the air after take off
•
if a force acts directly through the centre
of mass of an object, then linear acceleration
will occur (Newton's second law), no turning or
rotating
•
example :
– basketballer : force acts through CoM
therefore jumper does not rotate in air
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Module 2565 B1.2.25
OCR A Level Physical Education A 7875
Centre of Mass
CENTRE OF MASS - GENERATION OF ROTATION
FORCE ACTING AT TAKE-OFF NOT THROUGH
CoM
•
a force which acts eccentrically to the centre
of mass of a body will cause the body to begin
to rotate (will initiate angular acceleration)
•
this is because the force will have a moment
about the CoM and will cause turning
•
example :
– high jumper : force acts to one side of
CoM therefore jumper turns in air
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Module 2565 B1.2.26
OCR A Level Physical Education A 7875
Body Levers
LEVERS
class 1
effort in
muscle
E-P-L
class 2
JOINTS AS
LEVERS
pivot at
joint
load is force
applied
E-L-P
class 3
L-E-P
LEVERS
• levers have an pivot (fulcrum), effort
and load
•
and are a means of applying forces at a
distance from the source of the force
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Module 2565 B1.2.27
OCR A Level Physical Education A 7875
Body Levers
CLASSIFICATION OF LEVERS
CLASSIFICATION OF LEVERS
•
•
•
class 1 lever : pivot between effort and load
see-saw lever found rarely in the body
example : triceps / elbow
•
•
•
class 2 lever : load between pivot and effort
wheelbarrow lever, load bigger than effort
example : calf muscle / ankle
•
•
•
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class 3 lever : effort between pivot and load
mechanical disadvantage, effort bigger than load,
most common system found in body
example : quads / knee and biceps / elbow
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Module 2565 B1.2.28
OCR A Level Physical Education A 7875
Body Levers
EFFICIENCY OF LEVERS
angle between
effort and lever
arm
EFFICIENCY OF
LEVERS
length of
lever arm
distance between
effort and
fulcrum
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Module 2565 B1.2.29
OCR A Level Physical Education A 7875
Moment of Force
MOMENT OF FORCE - TORQUE
MOMENT of a FORCE (TORQUE)
PRINCIPLE of MOMENTS
•
•
•
•
•
•
•
moment = force x distance from
pivot to line of action of force
unit
newton metre Nm
example :
– moment = F x d
– d measured at right angles to F
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this law applies when a lever is
balanced
(When the arms of the lever are not
accelerating)
moments tend to turn a lever arm :
– clockwise (CW)
– or anticlockwise (ACW)
anticlockwise moment
= clockwise moment
Module 2565 B1.2.30
OCR A Level Physical Education A 7875
Moment of Force
CALCULATION OF EFFORT IN MUSCLE
FORCE IN TRICEPS MUSCLE a worked example
•
•
•
•
•
•
•
•
•
load (weight in hand is 20 kg)
= 20 x 10 (each kg weighs 10 N)
= 200 N
distance of load to pivot (hand to elbow joint) = 0.3 m
anticlockwise moment (of load) = 200 x 0.3
= 60 Nm
distance of effort from pivot (triceps muscle insertion to elbow joint)
= 0.02 m
clockwise moment (of effort)
= effort x 0.02
ACW moment
= CW moment
60 Nm
= effort x 0.02
therefore
effort
= 60
0.02
effort = force in triceps muscle = 3000 N
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Module 2565 B1.2.31
OCR A Level Physical Education A 7875
Principal Axes of Rotation
PRINCIPAL AXES OF ROTATION
BODY PLANES & AXES
• plane
- an imaginary flat surface through the body
•
axis of rotation
- an imaginary line about which the body
rotates or spins, at right angles to the plane
•
vertical / longitudinal axis (V)
- whole body movements - twisting / turning,
spinning skater / discus / hammer /
ski turns
•
frontal axis (F)
- whole body movements include
somersaults, pole vault take off, sprinting
•
sagittal / transverse axis (S)
- whole body movements include cartwheel
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Module 2565 B1.2.32
OCR A Level Physical Education A 7875
Principal Axes of Rotation
BODY PLANES FOR MOVEMENT
PLANES :
• frontal
•
•
sagittal
- divides the body into left and right sections :
flexion, extension, dorsiflexion plantarflexion
- whole body movements include somersaults,
pole vault take off, sprinting
transverse
- divides the body into upper and lower
sections : medial / lateral rotation, supination,
pronation
- whole body movements - twisting / turning,
spinning skater / discus / hammer / ski turns
•
•
•
•
- divides body into front and back sections :
abduction, adduction, lateral flexion
- whole body movements include cartwheel
as a student you will have to identify the major planes
and axes in physical activity
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Module 2565 B1.2.33
OCR A Level Physical Education A 7875
Angular Motion
ANGULAR MOTION - TORQUE
MOMENT OF FORCE
TORQUE
COUPLE
• these are all terms which describe the
turning effect produced by a force
• when it acts eccentrically (to one
side of) to an axis of rotation
• moment = F x d
•
such a moment would cause
rotation / turning
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Module 2565 B1.2.34
OCR A Level Physical Education A 7875
Angular Motion
ANGULAR MOTION
ANALOGUES OF NEWTON’s LAWS
NEWTON’s 1ST LAW
• rate of spinning will remain the same provided no
torque acts
• strictly - angular momentum remains the same (is
conserved)
• see later for explanation of angular momentum
NEWTON’s 2ND LAW
• if a torque acts on a spinning system then this will
change the angular velocity of the system
• the rate of spinning will speed up or slow down
NEWTON’s 3RD LAW
• if a torque acts from one body onto another
• then the first experiences an equal and opposite
torque in the opposite direction
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Module 2565 B1.2.35
OCR A Level Physical Education A 7875
Angular Motion - Measurements
ANGLE - ANGULAR DISPLACEMENT
ANGLE (ANGULAR DISPLACEMENT)
• to be scientifically correct angle should not be
measured in degrees, but in RADIANS (r)
•
angle
•
360
–
–
–
and
•
Previous
= arc length = l
radius of arc r
degrees =
180o
=
90o
=
30o
=
so on (see
2 x p radians = 6.28 radians
pr
= 3.14 r
1/2 p r
= 1.57 r
1/6 p r
= 0.52 r
maths text book for more)
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Module 2565 B1.2.36
OCR A Level Physical Education A 7875
Angular Motion - Measurements
ANGULAR VELOCITY
ANGULAR VELOCITY
•
= angle turned through per second
 w
= angle turned through
= q
time taken
t
 w
= Greek letter omega
•
•
•
•
this is rate of spin, most easily understood as
revolutions per second (revs per sec)
revs per sec would have to be converted to the unit
radians per second (rs-1) for calculations
1 rev per second = 2 x p
= 6.28 rs-1
rates of spin apply to :
– tumbling gymnasts
– trampolinists (piked straight and tucked somersaults)
– discus and hammer throwers
– spinning skaters
– skiers turning and twisting between slalom gates
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Module 2565 B1.2.37
OCR A Level Physical Education A 7875
Angular Motion - Measurements
ANGULAR ACCELERATION
ANGULAR ACCELERATION
• rate of change of angular velocity
•
•
•
•
•
Previous
angular acceleration
= change of angular velocity
time taken
A = w2 - w1
t
note similarity of formula with linear
motion
used when rates of spin increase or
decrease
example :
– hammer thrower
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Module 2565 B1.2.38
OCR A Level Physical Education A 7875
Angular Motion - Moment of Inertia
MOMENT OF INERTIA
MOMENT OF INERTIA (MI)
• the equivalent of mass for rotating systems
• rotational inertia
•
objects rotating with large MI require large
moments of forces / torque to change their
angular velocity
•
objects with small MI require small moments of
force / torque to change their angular velocity or w
•
MI depends on the spread of mass away from the
axis of spin, hence body shape
the more spread out the mass, the bigger the
MI
•
•
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unit
kilogramme metre squared
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kgm2
Module 2565 B1.2.39
OCR A Level Physical Education A 7875
Angular Motion - Moment of Inertia
MOMENT OF INERTIA
MOMENT OF INERTIA (MI)
• MI = SMr2
• MI depends on the spread of mass away from the axis of
spin, hence body shape
• the more spread out the mass, the bigger the MI
•
•
bodies with arms held out wide have large MI
the further the mass is away from the axis of rotation
increases the MI dramatically
•
•
•
sportspeople use this to control all spinning or turning movements
pikes and tucks are good examples of use of MI, both reduce MI
in the diagram, I is the MI for the left most pin man, and I has a value of
about 1 kgm2 for an average person
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Module 2565 B1.2.40
OCR A Level Physical Education A 7875
Angular Motion - Moment of Inertia
MOMENT OF INERTIA
The SPRINTER’S LEG
• when the leg is straight, the leg has
high MI about hip as axis
• therefore requires large force /
torque in groin muscle to swing leg
•
•
•
•
on the other hand when fully bent the
leg has low MI
therefore requires low force /
torque in groin muscle to swing leg
so a sprinter tends to bring the leg
through as bent as possible (heel as
close to backside as possible)
this is easier and faster the more
bent the leg
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Module 2565 B1.2.41
OCR A Level Physical Education A 7875
Conservation of Angular Momentum
CONSERVATION OF ANGULAR MOMENTUM
ANGULAR MOMENTUM (H)
• angular momentum = moment of inertia x angular velocity
= rotational inertia x rate of spin
•
H
=
Ix w
CONSERVATION of ANGULAR MOMENTUM
• this is a law of the universe which says that angular momentum of a spinning
body remains the same (provided no external forces act)
• a body which is spinning / twisting / tumbling will keep its value of H once the
movement has started
•
•
•
therefore if MI (I) changes by changing body shape
then w must also change to keep angular momentum (H) the same
if MI (I) increases (body spread out more) then w must decrease (rate of spin
gets less)
•
strictly, this is only exactly true if the body has no contact with its surroundings,
as for example a high diver doing piked or tucked somersaults in the air
but it is almost true for the spinning skater !
•
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Module 2565 B1.2.42
OCR A Level Physical Education A 7875
Conservation of Angular Momentum
CONSERVATION OF ANGULAR MOMENTUM - EXAMPLES
THE SPINNING SKATER
• arms wide - MI large - spin slowly
• arms narrow - MI small - spin quickly
THE TUMBLING GYMNAST
• body position open - MI large - spin
slowly
• body position tucked - MI small - spin
quickly
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Module 2565 B1.2.43
OCR A Level Physical Education A 7875
Conservation of Angular Momentum
CONSERVATION OF ANGULAR MOMENTUM - EXAMPLES
DANCER - SPIN JUMP
• the movement is initiated with arms
held wide - highest possible MI
• once she has taken off, angular
momentum is conserved
• flight shape has arms tucked across
chest - lowest possible MI
• therefore highest possible rate of spin
THE SLALOM SKIER
• slalom skier crouches on approach to
gate therefore with large turning MI
• as he / she passes the gate he / she
stands straight up (reducing MI)
• so turns rapidly past the gate, then
crouches again (increasing MI)
• to resume slow turn between gates
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Module 2565 B1.2.44
OCR A Level Physical Education A 7875
Conservation of Angular Momentum
CONSERVATION OF ANGULAR MOMENTUM - EXAMPLES
THE LONG JUMPER
BEFORE TAKE-OFF
• the jumper has an upward reaction
force acting on his / her take-off foot
• which acts eccentrically to the CoM
• and therefore causes clockwise rotation
of the jumper’s body after take-off
AFTER TAKE-OFF
• the jumper would rotate forwards and
land on his / her face
• unless he / she could minimise the rate
of rotation
•
•
this is done by making the MI as big as
possible
as in the hang or sail technique
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Module 2565 B1.2.45