4 OPOs MPs IN PROJECTING 1 maximum Horizontal

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

Projection Angle ( res ) Vhoriz Vvert Ø res less than 45º Ø long throw Ø long jump Ø Figure 12. 1 page 388 Ø res of 20° = Vhoriz almost 3 times greater than Vvert Ø res greater than 45º Ø volleyball jumps Ø high jump Ø Figure 12. 1 page 388 Ø res of 60° = Vvert more than 2 times greater than Vhoriz

Vector Composition Ø Find Resultant e. g. Resultant Velocity (Vres) Ø Pythagorean Theorem Ø Resultant² which is unknown = the sum of the squares of other 2 components which are known Ø Vres² = Vhorz² + Vvert² Ø Vres² = 4² + 3² Vres = 5 mps @ x°

FORCES Affecting Projectiles I. GRAVITY ü directed toward center of earth @ 9. 8 m/sec² ü decelerates on ascent, accelerates on descent II. DRAG ü results from airflow past projectile ü comprised of: 1. Profile/Form drag 2. Skin Friction/Surface drag

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

SKIN FRICTION/SURFACE DRAG Ø Secondary factor influencing magnitude of drag Ø Boundary layer of air “sticks” to projectile Ø rougher surfaces create more friction (“sticking”) Ø reduced using smooth surfaces, tight

Projecting for maximum Vvertical üg is resistive then motive ü Fdrag is always resistive in aerodynamics ü greater V of projectile = greater Fdrag ü on descent, acceleration influenced by Fdrag ü greater projection V = greater height achieved

Vvertical 1. Height of C of G at takeoff point (higher CG @ takeoff = higher apex in flight) 2. Vvert of C of G at takeoff (greater = higher) 3. Location of reaching fingertips @ apex see Figure 12. 4 on page 392

Vertical Projection with some Vhoriz Ø Tumbling - flip-flops increase ground reaction F Ø High Jump - carry body from takeoff to pit Women’s WR 2 m 09 / 1 m 78 tall [diff. 31 cm] Milt Ottey 2 m 32 / 1 m 77 tall [diff. 55 cm] Straddle vs Flop Figures 12. 5, 12. 6 on page 394 Ø Ø Ø Pole Vault - Vhorz critical for pole rotation

Vhorizontal Ø More common in sports Ø Fresistive are g, air resistance, ground friction Features for max. Vhoriz projections are: Ø Critical 1. v of release [faster = farther] most important 2. ht of release [higher = farther] 3. of release [see FIG 12. 8 on page 397]

Factors Affecting DHORZ of Projectiles

“Basic Biomechanics” by Susan J. Hall page 345

Vertical Target Ø darts, archery Ø FIG 12. 15 on page 406 Ø farther target requires more Vvert projection Horizontal Ø basketball, golf, shoes Ø BB rim diameter: = margin of error Ø FIG 12. 16 on page 408 Ø best BB shooters have greater shld flexion + more elbow