PROJECTILE MOTION

• Projectile


  An object or body thrown with an initial velocity and whose motion is influenced by the pull of gravity
• Projectile Motion


  • A combination of vertical and horizontal motions that are completely independent of each other
• Examples of projectile motion

  • sneezing
  • Firing a canon
  • Throwing a basketball
  • Water escaping a hose
  • Bike and skateboard stunts
• Descriptions of moving objects


  • An object which is moving through the air and not touching any surface - projectile
  • A falling skydiver with an open parachute - non projectile
  • Any object upon which air resistance is negligible - projectile
  • A free-falling object - projectile
  • An object upon which the only significant force is the force of gravity - projectile
  • A falling feather - non projectile
  • A falling feather in a vacuum chamber - projectile
• Trajectory


  The path of a projectile, determined by its vertical and horizontal motions
• Trajectory of a projectile

  • Height (dr) - the vertical displacement of a projectile
  • Range (dx) - the horizontal displacement of a projectile
• Projectile 1: Body Launched Horizontally (θ=0°)

  1. Vertical motion only

  2. Vx = Vo

  3. Vy = -gt
• Projectile II: Body Launched at a Certain Angle (90°>θ>0°)


  1. Vx = Vo cos(θ)

  2. Vy = Vo sin(θ)

  3. hmax - maximum height

  4. Xmax - maximum range

  5. Vx = constant along x
• When the effect of air resistance is significant, the range of a projectile is diminished and the path is not parabolic
• Sample Problem


  1. Vertical motion: dy = Viy*t + 1/2*a*t^2

  2. Horizontal motion: dx = Vix*t
• Sample Problem 2


  1. Upward vertical motion: Vy = Viy + a*t

  2. Horizontal motion: dx = Vix*t
• At maximum height, Vy = 0
• Vertical motion at max height: Vy^2 = Viy^2 + 2*a*dy