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Projectile motion parabola shape

  1. Jun 19, 2011 #1
    why the projectile motion's graph distance against inclination angle is parabola shape?
    ....thank you
  2. jcsd
  3. Jun 19, 2011 #2
    do u mean the shape of the distance x as a function of the angle ??
  4. Jun 19, 2011 #3


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    If you are talking about 2d projectile motion with distance v. time for any fixed angle above the horizontal then the graph will be a parabola because distance is quadratic in time i.e. d = v(initial)*t + 1/2*a*t^2.
  5. Jun 19, 2011 #4
  6. Jun 19, 2011 #5
    Because the horizontal velocity of the projectile is constant and the vertical velocity continuously decreases because of gravity and hence the distance the projectile traveled in a given time keeps on decreasing and horizontal distance remains the same. This results in a parabolic trajectory.
    Thank you.
  7. Jun 19, 2011 #6
    newton, my equation is s=([/2] (sin 2 angle))/ g
  8. Jun 19, 2011 #7


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    That's the equation for the maximum horizontal distance the projectile will travel (its range).

    But in order to determine the shape of the trajectory, you need to plot vertical postion vs. horizontal position (y vs. x).

    y varies quadratically with time.

    x varies linearly with time.

    If you eliminate time as a variable, you'll find that y varies quadratically with x.
  9. Jun 19, 2011 #8
    the lecturer only asks me why the graph of projectile motion is parabolic shape? then what answer should i give??
  10. Jun 19, 2011 #9
    is it because of the graph is sin graph??s directly proportional to sin angle??
  11. Jun 19, 2011 #10


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    I just explained why in my previous post.
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