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Homework Help: Quick Question

  1. Nov 19, 2008 #1
    1. The problem statement, all variables and given/known data

    So we did a lab this week in my physics class.

    We had a car on a horizontal table, that was attached to a string with weights (The weights were over the edge of the table.) We then calculated the experimental acceleration and the calculated acceleration. These numbers were different.

    My teacher asked us "What was causing the difference between the calculated acceleration and experimental acceleration..."
    He also mentioned something to do with Newton's laws.

    Do you know the answer/Can help me out?

    HUMAN ERROR IS NOT THE ANSWER...And the the time was taken by a electronic device.

    2. Relevant equations

    g = 9.8 m/s

    3. The attempt at a solution

    I really dont know how to start! whats causing the difference!
    Last edited: Nov 19, 2008
  2. jcsd
  3. Nov 19, 2008 #2
    Friction, human reaction time. F = d(mv)/dt

    Since friction affects net force, reaction affects time, one wouldnt expect to get the exact answer..
  4. Nov 19, 2008 #3
    I'm not really sure what you mean by human reaction time?

    Elaborate? like ... the time that i calculated forit to go? because it was takeen by a stop watch
  5. Nov 19, 2008 #4
    ok, human has a reaction time of about 0.19s. Which means you could have pressed the time too late, which means the time u measure is more than the the theoretically calculated time.
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