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Lecture 1

Kinesiology 2241A/B Lecture Notes - Lecture 1: Fosbury Flop, Resultant Force, Stick Figure


Department
Kinesiology
Course Code
Kinesiology 2241A/B
Professor
Thomas Richard Jenkyn
Lecture
1

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Requirements+
10#font#-1.5#line#spacing#
CH#12#reference#movement#-also#figure#1.2#pg#328
Assignment+
Analyze#"Fosbury#Flop"#or#"the#Flop"#
4+Questions+
1. Divide#the#high#jump#task#into#two#phases:#the#first#is#when#the#jumper#is#on#the#
ground#and#approaching#the#bar,#the#second#is#when#the#jumper#is#airborne.#In#which#
phase#is#the#pathway#of#the#overall#center#of#mass#of#the#jumper#under#the#jumper’s#
control,#and#why?
2. At#the#moment#of#takeoff#(between#the#two#phases)#when#the#jumper#is#still#on#the#
ground,#what#effect#does#the#movement#upward#of#the#leading#leg#and#the#arms#have#
on#the#jumper’s#overall#center#of#mass?
3. During#the#final#part#of#the#approach#phase,#what#causes#the#jumper’s#body#to#
move#from#a#position#leaning#away#from#the#landing#pad#to#a#position#leaning#slightly#
toward#the#landing#pad?#
i) A#mark#(such#as#an#‘X’)#at#the#location#of#the#jumper’s#overall#center#of#mass,
iii) The#resultant#force#vector#acting#at#the#overall#center#of#mass,
iv) The#resultant#torque#acting#at#the#overall#center#of#mass.
4. Use#the#figures#below#(Figure#12.5b#and#Figure#12.6a#from#page#394#of#the#
textbook)#as#references.#Draw#a#‘stick#figure#that#represents#the#position#of#the#
jumper#at,#a)#the#instant#of#takeoff,#and#b)#the#point#of#maximum#height#of#the#overall#
center#of#mass.#On#each#drawing#label# the#following:
Chapter+12+Readings+
CG#follows#PRESCRIBED#parabolic#path#(after#take#off)
-
Slow#takeoff#velocity#=#air-drag#force#very#little#compared#to#body-weight#
force#
Gravity#reduces#vertical#velocity#AFTER#take#off#(continues#till# at#0)
-
Jumper#need#enough#horizontal#velocity#to#move#over#the#bar#
Need#to#INCREASE#horizontal#resistance#(decrease#if#there#is#a#
strong#tail#wind)#
§
Air-resistance#force#(strong#head#wind)#-this#will#decrease#the#horizontal#
velocity#
Angle#determines#magnitude#
-
High+Jumping+
Rotary#+#linear#motion#caused#by#ECCENTRIC#force#applied#to#diver#by#
RECOILING#springboard#
-
FIGURE+1.2
Can#assume#that#wind#has#no#reaction#=#horizontal#velocity#component#doesn’t#
change#
-
Each#body#pt#positioned#at#same#time#to#clear#
Highest#CG#reached#as#it#passes#vertical#alignment#w/#bar#(max#
effectiveness)#
Highest#jump#=#CG#projected#as#high#as#possible#
-
Higher#greater#vertical#component#=#better#chance#of#raising#CG#
during#flight#
§
Goal#=#lgest#V#takeoff#w/#H#component#to#pass#over#bar
§
Max#vertical#=#max#vertical#velocity#at#takeoff#
Being#taller#gives#advantage
Max#vertical#
-
High+Jumping+Cont.+
Both#have#same#vertical#velocity#at#takeoff#
-
Decrease#in#horizontal#velocity#
-
Jumping+Techniques+
Back+Layout+Technique+
Low#arms#+#flexed#knees#
-
All#segments#except#for#pts#immediately#passing#the#bar#in#a#lowered#position#
-
Back#flexibility# is#important#
-
This#would#reduce#horizontal#component#
§
VV#=#4m/sec,#takeoff#angle#=#40-48#(believes#it#should#be#90#to#increase#
VV)
6m/sec#at#touchdown#+#3m/sec#@#takeoff
-
AKA+the+fosbury+flop
Advantage#b/c#CG#@#takeoff#is#higher#
-
Result#=#few#cms#in#CG#height#
High#arms#+#high#knees
-
Higher#CG#at#peak#flight#
-
Torso#+#lead#leg#flexion#
-
Straddle+Technique+
1#foot#takeoff#(ultimate#jump)
-
All#pts#expect#for#over#bar#as#low#as#possible#
-
Forward+Dive+Technique
Straight#line#perpendicular#to#the#bar
-
Followed#by#arc#
-
Change#angle#via#width#
-
Jumper#moves#away#from#pathway#to#overcome#height
§
When#C#is#higer#during#leap#=#overcomes#height#
C#force#pulls#jumper#away#from#the#arc#-leans#toward#center#(centripetal#
force)
Centrifugal#force#immediately#affects#-need#to#be#balanced#syntripidal#force#
-
Increase#r#=#decrease#q#therefore#less#curve#
§
Q=Vsqure#x#R
Longer#arc#=#less#stress#on#ankles#-4/6/10#step#approach
-
Follow#curve#as#closely#as#possible
Directly#above#L#foot#in#take#off#
-
Plant#R#foot#at#last#base#of#support#of#curve
-
Pathway
Lab$#2$Due$March$4th
Friday,#February#20,#2015
1:54#PM
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