4 OPO

1
4 OPOs / MPs IN PROJECTING

• 1. maximum Horizontal distance (Dhoriz)
• 2. maximum Vertical distance (Dvert)
• 3. maximum Accuracy
• 4. maximum Accuracy with Speed

2
Projection Angle (?res ) Vhoriz
Vvert

• ?res less than 45º
• long throw
• long jump
• Figure 12.1 page 388
• ?res of 20 Vhoriz almost 3 times greater than
  Vvert

• ?res greater than 45º
• volleyball jumps
• high jump
• Figure 12.1 page 388
• ?res of 60 Vvert more than 2 times greater
  than Vhoriz

3
Vector Composition

• Find Resultant e.g. Resultant Velocity (Vres)
• Pythagorean Theorem
• Resultant² which is unknown the sum of the
  squares of other 2 components which are known
• Vres² Vhorz² Vvert²
• Vres² 4² 3²Vres 5 mps _at_ x

4
FORCES Affecting Projectiles

• I. GRAVITY
• directed toward center of earth _at_ 9.8m/sec²
• decelerates on ascent, accelerates on descent
• II. DRAG
• results from airflow past projectile
• comprised of
• 1. Profile/Form drag
• 2. Skin Friction/Surface drag

5
PROFILE/FORM DRAG

• Primary factor influencing magnitude of drag
• magnitude is proportional to the size/area of
  leading edge of projectile (larger size more
  drag)
• higher pressure zone on leading side and a lower
  pressure zone on trailing side of projectile
• suction on trailing side
• reduced by streamlining

6
SKIN FRICTION/SURFACE DRAG

• Secondary factor influencing magnitude of drag
• Boundary layer of air sticks to projectile
• rougher surfaces create more friction
  (sticking)
• reduced using smooth surfaces, tight fitting wear

7
Projecting for maximum Vvertical

• g is resistive then motive
• Fdrag is always resistive in aerodynamics
• greater V of projectile greater Fdrag
• on descent, acceleration influenced by Fdrag
• greater projection V greater height achieved

8
Vvertical

• 1. Height of C of G at takeoff point(higher CG _at_
  takeoff higher apex in flight)
• 2. Vvert of C of G at takeoff (greater higher)
• 3. Location of reaching fingertips _at_ apex see
  Figure 12.4 on page 392

9
Vertical Projection with some Vhoriz

• Tumbling - flip-flops increase ground reaction F
  
• High Jump - carry body from takeoff to pit
• Womens WR 2m09 / 1m78 tall diff. 31cmMilt
  Ottey 2m32 / 1m77 tall diff. 55cm
• Straddle vs Flop Figures 12.5, 12.6 on page 394
• Pole Vault - Vhorz critical for pole rotation

10
Vhorizontal

• More common in sports
• Fresistive are g, air resistance, ground
  friction
• Critical Features for max. Vhoriz projections
  are
• 1. v of release faster farther most
  important
• 2. ht of release higher farther
• 3. ? of release see FIG 12.8 on page 397
• see FIG 12.9 on page 399

11
Factors Affecting DHORZ of Projectiles
12
Basic Biomechanics by Susan J. Hall page 345
13
Vertical Target Horizontal Target

• darts, archery
• FIG 12.15 on page 406
• farther target requires more Vvert projection

• basketball, golf, shoes
• BB rim diameter? ? ? margin of error
• FIG 12.16 on page 408
• best BB shooters have greater shld flexion more
  elbow extension at release