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Homework Help: Air track glider Lab Help!

  1. Oct 26, 2012 #1
    1. The problem statement, all variables and given/known data

    Okay, so I did a lab for my intro to mechanics physics class the other day and my lab report is due at 5pm tonight and I am having A LOT of trouble.
    The lab was a frictionless air track glider on a horizontal surface with a fixed mass M connected by a massless string to a hanging mass m, which we changed each trial in order to prove newtons second law, F= ma.
    The questions I am having trouble with are:

    1. Suppose the string connecting M and m is cut during their motion. Explain the subsequent motion of each mass. (Hint: comment on the subsequent velocity and acceleration of each mass)

    2. In case the acceleration of the system is very small, we can naively estimate that T=mg .
    Calculate the “actual” tension T in the string for one value of the acceleration and represent the difference between “actual” and “naive estimation” as a % difference.

    3. During the experiment we assume that the air track is frictionless. But there is in fact a small amount of friction between the glider and the track. Explain how measuring the glider's acceleration for a full bounce (glider moves up and down the track) helps to minimize the affects for friction? How would your experimental value of g change (smaller or larger) if you only measured the glider going down the track? How would your experimental value of g change (smaller or larger) if you only measured the gliders acceleration coming up the track? (Note: you do not have to offer a quantitative answer.)

    2. Relevant equations

    acceleration= mg/ (m + m)

    3. The attempt at a solution

    I don't even know where to begin. Please, any help is greatly appreciated. I am a learning disabled student so vague explanations tend to make me extremely confused. It would be wonderful if someone could just provide me with a straight forward and detailed method of how to approach each problem so that I am on the right track and can then answer the questions myself.
    Thank you so much!!
  2. jcsd
  3. Oct 26, 2012 #2


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    Staff: Mentor

    As you have learned via PM, you must show some work and effort on your part before we can be of tutorial help. That's very clear in the Rules link at the top of the page.

    How many questions have you answered so far in this lab? Can you post those and your answers to them?

    What are your thoughts on the questions that you posted above. Start with #1 -- What is going on before the string is cut? What are the motions of the two masses before? And what changes (in terms of forces) when the string is cut? Show us a free body diagram (FBD) for each mass before and after the string is cut.
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