Center of Gravity

Why do some things tip easily while others are stable?

As you can see from the example above, when the center of gravity is outside the base of the object it will tip. That suggests the general rule: it will be stable if it is low and wide. That is, keep the center of gravity low and the base wide!

Not only is a larger torque needed to tip an object that is wide and low, but the center of gravity has to be lifted higher for the low and wide object. As a result the work needed to tilt the object is larger.

Left: a “tall and narrow” object can be more easily tipped over.

Right: a “low and wide” object is more difficult to tip.

You can see from the dashed lines the amount the center of gravity must be lifted to tip over the object.

What are applications of this rule? Autos and trucks that are narrower and have high center of gravities are less stable against rollover. Football players and wrestlers are taught to get down low and spread your feet apart. This stance follows the “low and wide” rule making your body more stable and difficult to knock over. Your opponent, in order to knock you over, would have to exert a force to lift up your center of gravity and then push you over. If you simply stood upright, with your feet close together, you would be “tall and narrow” and your opponent would have less difficulty pushing you and your center of gravity.


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