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Chapter 3 Projectile Motion Notes

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e.g. throwing a baseball, cannon, ball rolling off table. 2 independent 'components' of motion: ... Projectiles: stone thrown in air, cannon ball, etc. ... – PowerPoint PPT presentation

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Title: Chapter 3 Projectile Motion Notes


1
Chapter 3 Projectile Motion Notes
2
Introduction
  • Nonlinear Motion- Motion along a curved path.
    e.g. throwing a baseball, cannon, ball rolling
    off table.
  • 2 independent components of motion
  • Horizontal remains constant w/o a force acting
    on it.
  • Vertical changes w/ time, g pulls object ? at
    10m/s/s.
  • ? Combined effects produce a curved path,
    however, neither component affects the other.
  • Vectors (arrows) help us understand this motion.

3
3.1 Vector and Scalar Quantities
  • Vector quantity A quantity that requires both
    magnitude direction.
  • e.g. velocity, acceleration
  • Scalar quantity A quantity that is described by
    magnitude only. Can be added, subtracted,
    multiplied divided.
  • e.g. mass, volume time
  • Arrows are used to represent vector quantities.
  • length of arrow magnitude
  • direction of arrow direction of vector
    quantity

4
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5
3.2 Velocity Vectors
  • Follow on the Board
  • Suppose an airplane is flying north at 100km/h
    and there is a tailwind blowing north at a
    velocity of 20km/h.
  • Suppose the same airplane turns around and flies
    into the wind.
  • Suppose an airplane flying north at 80km/h caught
    a strong crosswind of 60km/h blowing west to east.

6
3.2 Continued
  • Resultant the result of adding two vectors.
  • How do you find the resultant?
  • Vectors at right angles
  • Draw 2 vectors with tails touching
  • Draw parallel projection of each vector with
    dashed lines
  • Draw the diagonal (from point where tails are
    touching)
  • Vectors not at right angles
  • Form a parallelogram, the resultant is its
    diagonal.
  • Note To add 2 vectors that are equal in
    magnitude at right angles, we use a square.
    The diagonal is the square root of 2 or 1.414
    times the length of one of its sides.

7
3.3 Components of Vectors
  • Any vector can be broken down into its vertical
    and horizontal vectors, called components.
  • Resolution process of determining the components
    of a vector. (p. 32, Figure 3.7)
  • Vertical and Horizontal lines are drawn from the
    tail of the vector.
  • A rectangle is drawn that encloses the vector as
    its diagonal.
  • Sides of the rectangle are the desired components.

8
3.4 Projectile Motion
  • Projectiles stone thrown in air, cannon ball,
    etc.
  • Projectile Motion
  • ?Horizontal velocity remains constant when no
    horizontal force acts on projectile.
  • ? Vertical velocity changes dues to gravity.
  • Combined affect produces curved path, parabola.

9
3.5 Upwardly Launched Projectiles
  • No gravity projectile follows straight-line
    path.
  • With gravity projectile falls beneath line,
    same vertical distance it would fall from rest.
  • d ½ gt2 or d 5t2

10
3.5 Continued
  • Figure 3.11, p.36
  • Horizontal component is always the same
  • Vertical component changes
  • Resultant diagonal of rectangle formed
  • Figure 3.12, p.36
  • Initial velocity is greater due to increase in
    angle higher path
  • Figure 3.13, p.36
  • Paths of projectiles with same initial speed but
    different projection angles.
  • Projectiles reach different height horizontal
    distances.
  • Distance is the same for projectiles launched at
    angles that add up to 90 degrees.
  • Maximum range or distance is obtained at 45
    degree angle
  • If air resistance is small, it will take the same
    amount of time for projectile to reach its max
    height as it does to fall
  • For short range projectiles, assume ground is
    flat.
  • Long range projectiles, account for earths
    curvature.

11
3.6 Fast-Moving Projectiles-Satellites
  • Earth Satellite a projectile traveling fast
    enough to fall around the earth rather than into
    it.
  • ? This speed is 8 km/s or 18,000 mi/h
  • Satellites orbit above earths atmosphere in
    order to avoid air drag and burning up.
  • ?Cant avoid gravity!
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