Toppling

A tilted object will topple if the line of action of its weight passes beyond the pivotA uniform block will topple if the tan of its angle of tilt is greater than the ratio of the width to the height.i.e. if tanθ > (w/h).The pivot is the edge of the base that the object tilts about. While the line of action of the weight falls inside the pivot, the weight has a moment that pulls the object back to its upright position. Once the line of action passes beyond the pivot, the moment of the weight acts in the other direction and the object topples over.For a uniform block of width w and height h, the centre of mass is w/2 from the pivot and h/2 above the base. The weight acts directly above the pivot when tanθ = (w/2) / (h/2) = w/h.For example, a uniform block of width 0.2 m and height 0.8 m topples if tanθ > 0.25, i.e. if it is tilted more than 14.0°.An object with a wide base and a low centre of mass can be tilted further before it topples, so it is more stable.A block can also be tipped by a horizontal push F at height d. It starts to tip about its edge when the moment of the push equals the moment of the weight: Fd = W(w/2).