Transcript 100 Essential Things you Didn`t Know you Didn`t Know about Sport

World 100m running record progression: men
Swimmers Improved Much Faster Than Runners
Men’s 400m run: 43.8 (1968) to 43.18 (2011)
Men’s 100m swim: 52.2 (1968) to 46.91 (2011)
Ages of world records
11 women’s world records
are more than 20 yrs old
2 men’s records
are more than 20 years old
The Triathlon is Biased !
Winner spent 16.7% of the time swimming, 28.3% running,
0.8% in transitions, and 54.2% cycling !
The Equitempered Triathlon
Roughly equal time on each discipline
Current event
1.5 km swim + 40 km bike ride +10 km run
Better to keep the total time roughly the same – say 1 hr 48m
with equal 36 min time on each of the three stages
New event should be
3 km swim + 24 km bike ride + 12 km run
A Major Improvement !
Why Carry Do Tightrope Walkers Carry
Long Poles ?
Phillipe Petit, 1974
Don’t try this at home!
….and don’t wear bell-bottomed trousers
Inertia
high
low
• High inertia
Slow to move
• Low inertia
Quick to move
Mass M
Average radius R
mass spread C
Moment of Inertia = C  Mass  (Radius)2
Large inertia means you wobble more slowly
Period of wobble oscillation  (inertia)
Racing Bikes
re does your centre
of mass go ?
Stable
Unstable
Inertia in Sports





Divers
Skaters
Tennis players
Cyclists
Runners
Decreasing inertia
Increases rate
of spin:   1/r2
Rigging Rowing Eights
Rowing Has Its Moments
+N
F
and
-N
F
The Wiggling Boat
s
Moment on boat = -Ns + N(s+r) - N(s+2r) + N(s+3r) = +2Nr
Then, half a stroke later…N reverses to –N and..
Moment on boat = -2Nr
The Italian Rig
s
r
r
r
Moment = -Ns + N(s+r) + N(s+2r) - N(s+3r) = 0
No wiggle!
Four no-wiggle rigs for eights
‘Italian tandem Rig ’
Moment = 1-2-3+4+5-6-7+8 = 0
New*
Moment = 1-2-3+4-5+6+7-8 = 0
‘German Rig’
Moment = 1-2+3-4-5+6-7+8 = 0
New*
Moment = 1+2-3-4-5-6+7+8 = 0
Canada used the German rig to win 2008 Olympics !
1-2+3-4-5+6-7+8 = 0
Naim Suleymanoglu (b.1967) lifts 3 times his body weight (= 64kg)
Weight Classes
Why do we have them in
boxing, wrestling, judo and weightlifting?
But not in
Shot put, hammer, rowing, …..?
Why not height classes in high jump and basketball?
Strength versus Size
Strength is proportional to area

R2
Weight is proportional to volume  R3
Strength and Weight
strength  (weight)2/3
Giants eventually break!
(strength)3  (weight)2
Air Drag
 Speed V
Area, A(Bolt)
Mass of tube of air swept in time t is   A’  V  t = ma
 = air density
A’ = c  A(runner) is the ‘effective’ body area
c = drag factor
Drag force from still air = -maV /t = - c A V2
Drag force with wind speed W = - c A (V
Following wind is + and Headwind is –
-
W)2
Running around in the Wind
Drag force with wind speed W is  (V - W)2
Power needed = Force x velocity  V(V - W)2
Following wind is + and Headwind is –
Disadvantage of headwind and crosswind beats
the advantage of a tailwind of the same magnitude
K(V+W)2
K(V2+W2)
Drag
round square
track
K(V-W)2
Wind speed W in this direction
Runner runs at speed V in still air
K(V2+W2)
Drag Force per lap = 4K(V2 + W2)  4KV2
K = constant
It’s always slower running laps in the wind
Windy 400m- 10,000m races will be slower
Steady Pace Is Always More Economical
Go at speed U for dist x then at W = U for dist y = x/
or
Go at speed ½ (U + W) for dist x+ y in the same time so  = 1
Change speed
x at U
y at W
x + y at ½ (U + W)
Same speed all the way
Work needed  ( speed)3  time
(Work at varied pace) = 1 + 3( - 1)2/ ( + 1)2  1
(Work at steady pace)
The Velodrome
Heated air at track level
Means
Faster cycling
Hot air rises !
Drag force from still air  air c A V2
Air Density Falls with Temperature
Air Drag at Track Level in the London Velodrome
Drag Force  air × frontal area × V2
Just like an ‘altitude-assisted’ performance
Worth 1.5 sec over 4K pursuit