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(Magnets) Is the attractive force stronger than the repulsive force?

  1. Dec 4, 2011 #1
    Recently I've seen this video
    and after watching that I ask is this true? Is the attractive force between two identical magnets distanced away from each other stronger than the repulsive force at the same distance? Is the conclusion of demonstration neglecting any theories?

    I would like to design an experiment to prove or disprove my second question. I have an idea for an experiment it is fairly simple though. I'm not sure if the results I'd attain could be used to prove or disprove anything as I'm unsure of my idea:
    I intend to use two ring magnets. A pencil or something similar (to be used as a make-shift track for the two magnets) is passed through the two ring magnets. One ring magnet will remain stationary and the other one will be held a fixed distance away from the first one, non-stationary. Using a stop watch I'll measure for how long the non-stationary is displaced by magnetism for both attraction and repulsion (I'll have to be really quick with the stopwatch I may have to do this several times and take averages).
    I'll measure the total displacement for each case also (making sure the track is parallel to the horizon for this experiment), in the case of attraction it is the fixed distance I was talking about (this is one thing I'm unsure of doing). It is known that for both cases the initial velocity of each magnet is 0ms^-1, I have measure the displacement for both cases and also time.
    Using the kinematic equation s = ut + (at^2)/2 I can work out the acceleration of the ring magnet for both cases and hence use F = ma (Newton's 2nd law, after finding the mass of the ring magnets, both of which are approximately identical) to calculate and compare the forces of both attraction and repulsion hence draw a conclusion from there.

    Is this a viable experiment to test the forces of magnetism? I'm seeking advice as to whether or not there is a different experiment that I can carry out (keeping in mind my limitations as a student) to test this. I would also like some feed back or any advices on improving the experiment idea that I've come up with. I'm also interested in whether or not that video's conclusion is true or not, as in the theories behind the results I'd like to know why he got the results he got or why he did/didn't get the results he should have gotten. Basically I'd like to build my understanding on this so I'd like to know any theories related to this question (I'm sorry I feel like I'm repeating myself).

    I'm sorry if I'm asking too much and if I posted this in the wrong section but if possible I'd really like a lot of help and advice on this, all the articles I've read so far are not refined enough or specific to this question.
    Thanks a lot for reading all this and even more thanks if you help me!
  2. jcsd
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