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Homework Help: How do you devrive equations in kinematics

  1. Aug 27, 2009 #1
    Okay, I really need to know exactly how to derive these formulas

    (delta)x = (average)v*t

    (average)v = v(subscript)f + v(subscript)i/2

    a = v(subscript) - v(subscript)i/t

    My physics teacher says you can use these 3 formulas to answer any one dimension kinematics problem if the acceleration is constant. Now how do I derive these to get the formula. Please help I am very desperate and I need to know soon.
  2. jcsd
  3. Aug 27, 2009 #2


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    Well distance=speed*time and acceleration is defined as the rate of change of velocity per unit time or (change in velocity)/time
  4. Aug 27, 2009 #3

    Andrew Mason

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    These formulae are only valid if you have constant acceleration. You can derive these without calculus (well, you are using calculus but it is simple geometry) by plotting a speed vs. time diagram of an object moving with constant acceleration.

    What does the area under the graph represent? (hint: area = height x width; height = v and width = [itex]\Delta t[/itex]). How does the area relate to the maximum and minimum speeds? (think area of a triangle).

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