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Homework Help: Average Speed? How do I calculate?

  1. Mar 1, 2008 #1
    Average Speed? How do I calculate??

    How do I calculate average speed on a position time graph? Velocity time graph?

  2. jcsd
  3. Mar 1, 2008 #2
    On a position vs time graph, the average velocity is found by dividing the total displacement by the total time. In other words, (position at final point - position at initial point) / (time at final point - time at initial point).

    For a velocity vs time graph, you can simply do (Final velocity - initial velocity) / 2.
  4. Mar 1, 2008 #3
    For the velocity time graph, how do I get the average speed for the entire set of data? It starts at the origin, then goes up to (120,25) for A, and then the final point is F which is (720, -140)
  5. Mar 1, 2008 #4
    In that case you would have to find the total displacement of the object, and divide that by the time it traveled.

    To find the displacement on a V(t) graph, you need to look at the area under the curve. In this case, you would get two triangles, one above and one below the t axis (assuming the lines connecting your points are straight). Subtract the area of the triangle under the t axis from the area of the triangle above the t axis, and divide this by total time traveled. You are subtracting area below from area above because the object is traveling with a negative velocity (backwards) in the region below the t axis.
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