Projectile Motion characteristics and analysis procedures Objectives –Review characteristics of projectile motion (pp ) –Review factors influencing projectile motion –Present and explain calculation methods for analyzing projectile motion Homework – due Wednesday, Feb 18 –Problems 7,9,10 on page 347

Projectile motion characteristics It is a freely falling body, subject to only two forces – gravity and wind resistance May be dropped, or projected (1) vertically, (2) horizontally, or (3) obliquely Flight pattern is determined by initial velocity –Speed (V 0 ) –Direction (  )

Projectile motion (cont’d)

Projectile motion, cont;d

Projectile motion, cont’d

Ignoring air resistance, flight pattern is parabolic

Projectile motion, cont’d Effect of angle or projection on flight pattern

Projectile motion, cont’d Projectile height plays a role in optimal projection angle for horizontal distance

Projectile motion, cont’d If projection angle is constant, range increases directly with magnitude of velocity

Projectile motion, cont’d Resolving projectile motion into vertical and horizontal components – the first step in calculating motion parameters of interest V vert = V sin  V horiz = V cos 

Projectile motion equations –Maximum height when given time of flight (hw prob #7) h = ½ at 2, where t = ½ total flight time –Maximum height when given initial velocity (hw prob #9) –Time of flight when given initial velocity (hw probs # 9, 10) –Range, or horiz dist when given initial Velocity (hw probs 9,10) –If time is calculated first, using above equation (hw probs 9,10) this reduces to: D horiz = V horiz T = V cos  T

Summary This chapter introduced basic concepts related to kinetics Several types of mechanical loads act on the human body. The distribution of force within a body structure is termed mechanical stress. Vectors quantities have magnitude & direction Vector problems may be solved by a graphic or a trigonometric approach. Kinematic concepts related to projectile motion were introduced Calculation methods for total body COM were presented