Mathematically, I understand how to approach a question and to figure out if the object will topple over on an incline.

I just want to understand why is it when the object's centre of mass is no longer pointing vertically downwards to a position within the block, then the object will then start to topple if I kept increasing the angle of the incline?

I tried explaining to myself that the COM is now high enough such that the moments acting at the COM is no longer in equilibrium with the rest of the object (which stops it from toppling over), however I still think my explanation misses something.


1 Answer 1


No your explanation is not missing anything.

Objects topple on inclined planes for the same reason they topple when pushed on horizontal planes.

If the object does not slide, the edge of the base will form a pivot about which the object can turn. Suppose the object is tilted gradually about this pivot then released. If the vertical line through the CG remains inside the base, then the weight forms a torque about this pivot which turns the object back onto its base. If this line falls outside the base, the torque due the the object's weight continues to turn the object away from its base.

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Source : BBC Bitesize Physics website

If the object does slide, accelerating down the incline, then the situation is more complex. See BowlOfRed's answer to What causes a tall box to tip over on an inclined plane?

  • $\begingroup$ @sammy gerbil If the vertical line through the CG is inside the base, why would the object turn? $\endgroup$ Commented Mar 12, 2017 at 1:35
  • $\begingroup$ @Mockingbird Thank you for your comment. I have edited my answer. $\endgroup$ Commented Mar 12, 2017 at 1:49

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