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Factors Influencing Movement

Factors Influencing Movement. 1. Magnitude of F or T 2. Inertial characteristics of object such as it’s mass, friction factors 3. Pathway available. Scalar quantity how fast only s = d/ t Donavan Bailey 100m 9.84 Michael Johnson 200m 10.11 + 9.12. Vector quantity

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Factors Influencing Movement

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  1. Factors Influencing Movement 1. Magnitude of F or T 2. Inertial characteristics of object such as it’s mass, friction factors 3. Pathway available

  2. Scalar quantity how fast only s = d/t Donavan Bailey 100m9.84 Michael Johnson 200m10.11 + 9.12 Vector quantity how fast and in what direction v = d/t stride length x stride frequency Linear Speed Linear Velocity

  3. Stride Length & Stride Frequency changes with running velocity FIGURE 10-3 on page 324“Basic Biomechanics” 4th edition by Susan J. Hall

  4. Page 280 from course text

  5. Johnson vs Bailey • at 5.6 seconds in 150m Match Race:Bailey 25 strides (4.46 strides per sec)Johnson 27 strides (4.48 strides per sec) • at 1996 Olympics:Bailey 9.84 for 100m (avg v = 10.16mps)Johnson 9.22 for 2nd 100m (avg v = 10.84mps) • Fastest recorded 10m segment in 100m race is 0.83 seconds giving a velocity of 12.1mps / 43.5km per hr

  6. Linear Acceleration • Vector quantity • changing speed OR changing direction • a = (v2 - v1)  (t2 - t1) • 2 is final and 1 is initial (velocity & time) • a is directly related to Force and only occurs when Force is applied or ceases • speeding up = + slowing down = -

  7. Universal Gravitation - Newton 1. Direct relationship between mass of 2 bodies and force of attraction between them 2. Indirect relationship between distance squared between 2 bodies and force of attraction between them 3. Falling bodies “attracted” to the ground by gaining speed @ 9.8mps per second 4. Upward projected bodies slow as above

  8. Body at rest No motion 1. Body at restOR 2. Body moving @ constant vOR 3. Body not changing direction Zero Velocity Zero Acceleration

  9. No change rare in sport Figure F.2 page 280 skydiving air = resistive Force g = motive Force F resistive = F motive Constant v Terminal v

  10. usually not a concern in study of motion v = d/t 40-50m in 1.11sec. average v = 9.01mps 1000m in 3:30min. average v = 4.76mps at a given point takeoff release impact Figure F.3 page 281 Average v Instantaneous v

  11. INERTIA - Newton’s 1st Law • “resistance then persistence” 1. body at rest remains so until a net Force acts to accelerate the body 2. body moves in the direction of applied Force @ constant v until - that Force is changed in magnitude or - a Force from another direction is applied

  12. Projecting Objects • Muscle torques are motive Force • Air resistance is a resistive Force • gravity resistive Force then motive Force • friction may be a resistive Force

  13. ACCELERATIONNewton’s 2nd Law • Inertia = sluggishness/resistance to change • Inertia is directly related to mass • a = F/m • a has a direct relationship with F • a has an indirect relationship with m

  14. Inward seeking exerted along the path of the radius of the arc Fc = ma (radial) Body wants to continue on original path greater m or v requires greater friction/grip F centripetal Reaction

  15. Pushing outward to get sufficient inwardF centripetal to stay on the desired curved path

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