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I Stacked boxes

  1. Dec 4, 2017 #1
    hi, i am studying about design the box carried on car.
    i am really stuck in how to draw free body diagram for when 3 or more boxes stack together on car running and braking. there are many example with 2 boxes but i dont know why i cant find any case with 3 or more boxes
    thanks in advance
  2. jcsd
  3. Dec 4, 2017 #2
    i have a question about the box carried on car: why the more boxes we stack the easier it fall down ? can anyone explain it in details
  4. Dec 4, 2017 #3


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    Science Advisor

    For a start, model one box, then vary its height.
  5. Dec 4, 2017 #4
    can you please give me detail. the thing is i think it is different when we use 1 high box and 3 boxes stacking with each other because they separate
  6. Dec 5, 2017 #5


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    Gold Member

    I don't understand your problem. If you must design a car with three boxes stacked on top of each other, it is quite the same diagram as when there are two boxes. Just that now there is another box introducing its own forces.

    As for the other question about more boxes making the boxes fall off easily, think about the center of mass of the boxes and then the support of the boxes. You should have learnt about stable, unstable and neutral equilibrium, how do you think that those relate to the question?
  7. Dec 5, 2017 #6


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    Science Advisor

    In practical terms: If they slide off each other, then a single box will slide off the roof too. The difference is in likelihood of toppling over, for which a high box is similar to multiple boxes.
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