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Homework Help: Help with lab report analyses

  1. May 13, 2012 #1
    1. The problem statement, all variables and given/known data I would like some analyses criticisms.

    This is what my analyses should contain

    - An analysis and discussion, which minimally should address the following:
    o A summary of your results.
    o A justification for procedural decisions.
    o An analysis of the graphs, and explanation of trends.
    o A comment about how the results support or refute the hypothesis.
    o A link between your results and research (can include the textbook as a reference). Include a discussion about the difference between static and kinetic coefficients of friction, and a statement about when friction could be considered helpful and when it is undesirable. If your hypothesis was refuted, be sure to explain why based on your research. Remember to cite any sources.
    o An explanation of errors and suggestions for improvements.

    2. Relevant equations

    3. The attempt at a solution
    In the quantitate experiment, the coefficient of static friction for sandpaper in contact with pinewood was 0.73 it had been obtained using a line of best fit as well as for the coefficient of kinetic friction which was 0.51. As for the quantitate procedure the frictional forces (static and kinetic) were determined by a camera for the very purpose of that you would be able to watch and monitor your results. The red line that was present in the graph was of a higher value then the blue one present and that is because the coefficient of static friction since it takes more force to accelerate something from rest then something that is not at rest. This very reason supports the data that was tabulated. The graph of Frictional forces vs. Normal force contained 2 functions in which one was linear as well as perfectly proportional (Ff static vs. Normal force) and one which was semi linear (Ff kinetic vs. Normal force). Therefore due to this experiment a linear line of best fit was more applicable to use than any other type of line.
    In the qualitative experiment adding more mass proved to make the object undergo more friction and as for material, the sandpaper on pinewood was shown to have more frictional forces (static and kinetic) then pinewood on pinewood. Surface area was constant but did not have an effect of increasing friction or decreasing friction.
    In the experiment the results that had been collected confirmed the hypothesis of adding more mass having larger frictional forces. When the Normal force increased the frictional forces both static and kinetic also increased. This has been supported by the graph and table that are present in this paper.
    The specific coefficient of static and kinetic friction for sandpaper in contact with pinewood is 0.6-0.8 according to http://www.docstoc.com/docs/27532325/Friction-coefficient-of-sandpaper-on-wood-Approximately-06-08 [Broken]. The coefficient of kinetic friction that was obtained is outside this range but it is in close proximity due to some errors.
    The static and kinetic coefficient differed in many ways. One is that the static coefficient is greater than or equal to the static frictional force divided by the normal force while the kinetic coefficient equal to the kinetic frictional force divided by the normal force. The static coefficient also differs in that it is greater than the coefficient of kinetic friction due to the fact that it takes more force to accelerate something from rest then something that is not at rest. Friction could be helpful or undesirable. Friction present in cargo ships reaching their destination is undesirable since they want to get to their destination as quickly as possible, but friction is helpful when you want to use brakes to slow down a car from crashing into another car.
    There were many errors present in the experiment. The fact that a person could have not accurately measured the static or kinetic force since the resolution of the eye prevents us from being able to measure where the spring went at very high accuracy. The dynamometer not being calibrated properly could have affected the readout of force since it needed to be calibrated at a certain mode. An improvement that could be implemented is a longer plank of wood so that you can record at a longer time interval and be able to more precisely measure the data.
    Last edited by a moderator: May 6, 2017
  2. jcsd
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