Designing a Car with Multiple Boxes: Free Body Diagrams

[Ken12332123123123]

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 don't know why i can't find any case with 3 or more boxes
thanks in advance

 

[Ken12332123123123]

hello,
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
thanks

 

[A.T.]

hello,
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
thanks

For a start, model one box, then vary its height.

 

[Ken12332123123123]

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

 

[lekh2003]

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

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 learned about stable, unstable and neutral equilibrium, how do you think that those relate to the question?

 

[A.T.]

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

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.