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Calculate the average speed from a bar graph

  1. Oct 4, 2007 #1
    Well I need to calculate the average speed from a bar graph and I do believe it said percent difference, then find the percent difference from the bar graph to my line graph. All I have is pictures of the bar graph, so can someone please tell me how to find the average speed and the percent difference? If you can thanks a lot. Sorry for the crappy pictures too.

  2. jcsd
  3. Oct 5, 2007 #2


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    Staff: Mentor

    It's difficult to understand the two graphs. There are 8 bars in one and 6 in the other. Do they represent the same time intervals, such that each bar has equal weight.

    Assuming one has N quantities vi, then how does one determine the average value?

    Then with the average value, take each vi, subtract the average, which will give the difference between the particular value and the average. How would one then determine the percent difference?


  4. Oct 5, 2007 #3
    Very sorry about that. The first picture on the left the numbers represent distance(cm) and the second picture represent the speed (cm/s). With the first picture too, the 2 strips that are the same length are the second and third from the left on the second picture. Right now this is velocity and it is testing with a spark generator(I think thats what it was). In lab we threaded this tape, a meter long, through the spark generator and tried to walk at a constant speed. Measured from 0-6(the dots created by the spark generator), 0-12, 0-18, 0-24, all the way up to 60 and then cut them at 6, 12, 18, 24, etc. Taped them onto this bar graph and now I got to find out the average speed and percent difference between this and the line graph I made. All I need is an equation there, I hope.
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