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

Linear Speed Linear Velocity Scalar quantity how fast only s = d/t Donavan Bailey 100m 9.84 Michael Johnson 200m 10.11 + 9.12 Vector quantity how fast and in what direction v = d/t stride length x stride frequency

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

Page 280 from course text

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

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 = -

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

Zero Velocity Zero Acceleration Body at rest No motion 1. Body at rest OR 2. Body moving @ constant v OR 3. Body not changing direction

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

Average v Instantaneous v 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

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

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

ACCELERATION Newton’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

F centripetal Reaction 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

Pushing outward to get sufficient inward F centripetal to stay on the desired curved path