Inline Skate

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Inline Skate Wheel

• Inline Skate Wheels Enhancement
• CCDP 2100A
• Morris Al Warras, Esin Albay, Hassan Hussin

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Who are our audience?

• Special quests
• President of Ottawa Inline Skate Club
• Mike Garvin
• Coach
• Stephane Tremblay

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Mechanical part - Rotational part

• ? ? / t Eq1 1

?
angular velocity ? angular
distance in radians t
time in seconds
Animation 1wheel rotation 2
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Mechanical part - Translational
part

• Vt
  tangential speed
• vt d/t Eq2 1 d distance covered
  in meter
• t
  time in seconds

B
A
s
S
tangential distance s r? Eq3 1
r radius of the wheel

? angular distance in radians
Animation 2wheel
rotation 2
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• s r? Eq3 1
  S tangential distance
• ? ? s / r Eq4
  r radius of the wheel
• 
  ? angular distance in
  radians
• By substituting Eq4 in Eq1 ,we will get
• ? ? / t Eq1 1
  ? angular velocity
• ? ? ?/t s/r/t s/t 1/r Eq5
• Since
• vt d/t Eq2 1
  Vt tangential speed
• 
  d distance
  covered in meter
  
  distance d s Eq61
  t time in seconds
• velocity v vt s/t Eq7 3
• ? vt 1/r Eq8 1
• ?vt wr Eq91

Relation between both
motions
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Final Equation Conclusion

• vt wr Eq91
• 
  Vt tangential speed
• 
  ? angular velocity
• 
  r radius of the wheel
• Eq9 shows that
• r ? vt

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In Practice

• Here are the common wheel sizes (radii)
• 27mm, 34mm, 36mm ,42mm ,45mm , 50 mm
• To demonstrate the relationship
• We hold w constant
• 4 revolutions per second
• w 8p/s
• vt 8p/s(r) (25.13 s-1)(r)

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Which best material is used? ?
PolyurethaneWhy??!!
Polyurethane

• High resistance to abrasion
• High tear strength
• Resistance to weather conditions.
• Heat resistance up to 850C
• Rigid and hard

Fig1 Internal wheel section
http//commons.wikimedia.org/wiki/ImageInline_Ska
te_Wheels.svg
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Polyurethanes Resistance to Abrasion
http//www.polyurethane-1.com/abrasion-resistant.h
tm
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Stokes Law

• µ 6pR?0 Eq10 4
• Where
• µ is the coefficient of friction
• ?0 is the viscosity coefficient (0.015 5.85)
• R is the universal gas law (8.314472)
• µ 156.7?0

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Videos

• For indoor skating
• http//youtube.com/watch?vAJuScOFKQxkfeaturerel
  ated
• For outdoor skating
• http//youtube.com/watch?vvausD8kY0OofeaturePla
  yListpDACAFDE64A8025ABindex8

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Derivatations

• SF Fapp Ff ma Eq10 3
• Ff friction force
• Fapp applied force by the skater (Fapp 4 kN)
• µ friction coefficient (3.9181-5.0151)
• m skater mass and wheel (m 80 kg)
• a acceleration (m/s2)
• a Fapp /m mg Eq11 3
• g gravitation acceleration(g 9.81 m/s2)

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Derivatations

• a vf vi / dt Eq12 3
• v is the velocity (f means final where i means
  initial vi0m/s)
• dt is the change in time (dt 1 s)
• Substituting Eq12 into Eq11
• vf vi / dt Fapp /m mg Eq13 3
• vf Fapp dt / m dtmg Eq143

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In Practice

• vf Fapp dt / m dtmgEq14
• vf -(9.81 m/s)m 50 m/s ...Eq15
• Speed decreases as friction coefficient increases
• We have a range for µ friction coefficient
  (3.9181-5.0151)

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Durability level of hardness

• Durability
• ?Friction coefficient

http//inlineottawa.com/content/tips/members/equip
_101/index.phpwheels
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Conclusion

• The wheel size and the material affect the
  performance and the speed
• Speed
• As
• Radius
• Durability
• Friction coefficient
• Performance
• As
• Durability

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References

• 1 Physics Department at Central Michigan
  University, Chapter 6 Angular Motion, October
  2007, http//www.phy.cmich.edu/people/andy/Physics
  110/Book/Chapters/Chapter6.htmb . Accessed on
  10th November
• 2http//www.baysideblades.com.au/inline_skates_d
  t/skate_wheels/hyper/hyper_pro_250_80_84.htm
  -Accessed on 14th November
• 3 F. P. Beer, E. R. Johnston, Jr., E. R.
  Eisenberg, W. E. Clausen, Vector Mechanics for
  Engineers Statics and Dynamics, 7th ed. Boston,
  MA McGraw Hill Higher Education, 2004.
• 4. J. V. Dawkins, Developments in Polymer
  Characterization 4, London Applied Science,
  c1978

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• Any questions????

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16 November 2007
Inline Skate Wheel Enhancement