Chapter 10 Linear Kinematics of Human Movement Basic

Kinematics of Projectile Motion What is the effect of gravity? (The force of gravity produces a constant acceleration of -9. 81 m/s 2 on bodies near the surface of the earth. ) Basic Biomechanics, 6 th edition By Susan J. Hall, Ph. D. 10 -2

Kinematics of Projectile Motion The pattern of change in the vertical velocity of a projectile is symmetrical about the apex gravity Basic Biomechanics, 6 th edition By Susan J. Hall, Ph. D. Vertical velocity decreases as the ball rises and increases as the ball falls due to the influence of gravitational force. 10 -3

Factors Influencing Projectile Trajectory What factors influence the trajectory (flight path) of a projectile? • projection angle - the direction of projection with respect to the horizontal Basic Biomechanics, 6 th edition By Susan J. Hall, Ph. D. 10 -4

This scaled diagram shows the size and shape of trajectories for an object projected at 10 m/s at different angles. Maximum height (m) Factors Influencing Projectile Trajectory 5 4 3 2 1 0 0 1 2 3 4 5 6 7 8 9 10 11 Range (distance) (m) Basic Biomechanics, 6 th edition By Susan J. Hall, Ph. D. 10 -5

Factors Influencing Projectile Trajectory The Effect of Projection Angle on Range (Relative Projection Height = 0) Projection Speed Angle Range (m/s) (degrees) (m) 10 10 10 20 30 40 45 50 60 70 80 Basic Biomechanics, 6 th edition By Susan J. Hall, Ph. D. 3. 49 6. 55 8. 83 10. 04 10. 19 10. 04 8. 83 6. 55 3. 49 10 -6

Factors Influencing Projectile Trajectory Projection angle is particularly important in shooting a basketball. A common error among novice players is shooting the ball with too flat a trajectory. Basic Biomechanics, 6 th edition By Susan J. Hall, Ph. D. 10 -7

Factors Influencing Projectile Trajectory What factors influence the trajectory (flight path) of a projectile? • projection speed - the magnitude of projection velocity Basic Biomechanics, 6 th edition By Susan J. Hall, Ph. D. 10 -8

Factors Influencing Projectile Trajectory The instantaneous velocity of the shot at the moment of release primarily determines the ultimate horizontal displacement of the shot. Basic Biomechanics, 6 th edition By Susan J. Hall, Ph. D. 10 -9

Factors Influencing Projectile Trajectory What factors influence the trajectory (flight path) of a projectile? • relative projection height - the difference between projection height and landing height Basic Biomechanics, 6 th edition By Susan J. Hall, Ph. D. 10 -10

Factors Influencing Projectile Trajectory FACTORS INFLUENCING PROJECTILE MOTION (Neglecting Air Resistance) Variable Factors of Influence Initial vertical velocity Flight time Relative projection height Horizontal velocity Horizontal displacement Relative projection height Initial vertical velocity Vertical displacement Relative projection height Trajectory Initial speed Projection angle Relative projection height Basic Biomechanics, 6 th edition By Susan J. Hall, Ph. D. 10 -11

Factors Influencing Projectile Trajectory The human body becomes a projectile during the airborne phase of a jump. Basic Biomechanics, 6 th edition By Susan J. Hall, Ph. D. 10 -12

Analyzing Projectile Motion The Equations of Constant Acceleration v 2 = v 1 + at (1) d = v 1 t + ½ at 2 (2) v 22 = v 12 + 2 ad (3) These equations may be used to relate linear kinematic quantities whenever acceleration (a) is a constant, unchanging value. Basic Biomechanics, 6 th edition By Susan J. Hall, Ph. D. 10 -13