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4 OPO’s / MP’s IN PROJECTING 1. maximum Horizontal distance (D horiz ) 2. maximum Vertical distance (D vert ) 3. maximum Accuracy 4. maximum Accuracy with Speed

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Projection Angle ( res ) V horiz V vert res less than 45º long throw long jump Figure 12.1 page 388 res of 20° = V horiz almost 3 times greater than V vert res greater than 45º volleyball jumps high jump Figure 12.1 page 388 res of 60° = V vert more than 2 times greater than V horiz

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Vector Composition Find Resultant e.g. Resultant Velocity (V res ) Pythagorean Theorem Resultant² which is unknown = the sum of the squares of other 2 components which are known V res² = V horz² + V vert² V res² = 4² + 3² V res = 5 mps @ x°

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

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

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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

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Projecting for maximum V vertical g is resistive then motive g is resistive then motive F drag is always resistive in aerodynamics F drag is always resistive in aerodynamics greater V of projectile = greater F drag greater V of projectile = greater F drag on descent, acceleration influenced by F drag on descent, acceleration influenced by F drag greater projection V = greater height achieved greater projection V = greater height achieved

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V vertical 1. Height of C of G at takeoff point (higher CG @ takeoff = higher apex in flight) 2. V vert of C of G at takeoff (greater = higher) 3. Location of reaching fingertips @ apex see Figure 12.4 on page 392

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Vertical Projection with some V horiz Tumbling - flip-flops increase ground reaction F High Jump - carry body from takeoff to pit Women’s WR 2m09 / 1m78 tall [diff. 31cm] Milt Ottey 2m32 / 1m77 tall [diff. 55cm] Straddle vs Flop Figures 12.5, 12.6 on page 394 Pole Vault - V horz critical for pole rotation

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V horizontal More common in sports F resistive are g, air resistance, ground friction Critical Features for max. V horiz 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

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Factors Affecting D HORZ of Projectiles

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“Basic Biomechanics” by Susan J. Hall page 345

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Vertical Target Horizontal Target darts, archery FIG 12.15 on page 406 farther target requires more V vert 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

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PROJECTILE MOTION An object launched into space without motive power of its own is called a projectile. If we neglect air resistance, the only force acting.

PROJECTILE MOTION An object launched into space without motive power of its own is called a projectile. If we neglect air resistance, the only force acting.

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