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Linear Kinematics Ch. 10
Appearance of motion form, pattern, sequencing of movement over time Kinematic Analysis of performance: *motor learning of new skill *rehab of injuried joint Qualitative (visual observation) Joint action Timing of movement Proper limb placement Quantitative (numerical measurement) Joint ROM distance time height Motor Development & Adapted PE Distance =? Displacement *scalar quantity vector quantity *measured along change in location the path point A point B *length length & direction Speed and Velocity Velocity (linear) : rate of change in motion Speed= Velocity= length (distance) displacement (pt. B-pt. A) change in time change in time
*displacement & velocity: vector equivalents to distance & speed Running speed=stride length x stride frequency Balance & stride length Runner’s stride length Factors effecting: Height Muscle fiber composition Footwear Fatigue Injury history % grade of surface Overstriding= ^ risk of hamstring strain Acceleration Speeding up or down Linear acceleration=rate of change in linear velocity a = change in v (v 2 – v 1 ) change in time Sprinter out of the blocks: Leaving v=3m/s, and 5m/s one second later What is sprinter’s acceleration? *best sprinter ^^^ stride frequency
"apex" = highest point in trajectory vertical velocity= 0 Factors Influencing Projectile Motion: Flight time (velocity & height) Horizontal displacement (velocity & ht.) Vertical displacement (vert. veloc & ht.) Trajectory (speed,angle,height) Factors influencing projectile trajectory
- Projection Angle Governs shape of trajectory: 1 of 3 shapes: vertical parabolic (R & L mirrors) horizontal = 1/2 parabola *Basketball=angle very impt!
- Projection Speed determines length & height of trajectory Range = horizontal displacement at landing
horizontal speed x flight time
- Relative Projection Height is the "landing height" ball released at 6 ft, lands at 0 ft.= 6 ft_ golf ball lands in tree >proj ht = ? Stand on hill, throw Frisbee > ^ flight time and ^ horizontal displacement
10 ft hill --3 ft (dog catches it) = 7 ft Optimal Projection Conditions: *when proj. ht. = 0 then 45 o angle (kick) *when proj. ht.= 5 ft then < 45 o angle (throw) *when proj. ht. = < 0 then > 45 o angle (basket b) when body is projectile (long, triple, high jump) should be 45 o since rel. proj. ht. = 0 but really 18 o to 27 o (because 45 o would decrease velocity of body) Analyzing Projectile Motion Initial velocity=a vector quantity, incorporating both angle & speed of projection *can be resolved >horizontal & vertical components Assumptions:
- d = v 1 t
- v 2 = v 2
1 & 3--reaffirmhorizontal velocity is a
constant #2--horizontal displacement is = horizontal velocity x time Constant acceleration relationships: When applied to vertical component of Projectile motion, acceleration is = -9.81m/s 2 can't be ignored or deleated ( = 0). However, v 1 = 0 when object is dropped so V 2 = at Vertical displacement d = (1/2) at 2 Object's vertical displacement, velocity &
gravitational acceleration v 2 = 2 ad When determining max height achieved: Apex velocity = 0 = v 1 0= v 1 + 2 ad
