Online Calculators since 2009
In addition to the revision notes for Centre of Mass. Types of Equilibrium on this page, you can also access the following Centre of Mass and Linear Momentum learning resources for Centre of Mass. Types of Equilibrium
|6.2||Centre of Mass. Types of Equilibrium|
In these revision notes for Centre of Mass. Types of Equilibrium, we cover the following key points:
Centre of mass (or gravity) is an equilibrium point inside an object, which is very special regarding the stability of the object itself. It is the only point of the object in which there will be no swings, slants, falls, etc., when an object is hanged through or placed on it.
Centre of mass of an object is usually denoted by C. The number of coordinates required to represent the point C depends on the number of dimensions the situation described involves. Thus, for a long and thin bar, there is only one coordinate needed as it is considered as a one-dimensional object. When the object is a kind of thin plate, two coordinates are enough for the centre of mass. When the object is voluminous, there are three coordinates for the centre of mass C needed.
There are three basic methods to determine the centre of mass in objects. They depend on the shape and physical properties of the objects.
Not all objects are equally stable when they are at rest. Some objects are more stable and they hardly move from their position when a force acts on them. On the other hand, for some other objects it a very small force is enough to make it fall sideways. Based on this criterion, there are 3 types of equilibrium:
In this kind of equilibrium, objects are very stable. If a small force acts on them, they shake around but finally they regain the initial position. The condition to have stable equilibrium is
where yC is the vertical coordinate of the centre of gravity C and h is the height of the object.
Unstable equilibrium is the opposite of stable equilibrium, i.e. a very small force is enough to make an object topple sideways. In other words, a much greater effort is needed to re-establish the equilibrium than to distort it. The condition to have unstable equilibrium is
In this kind of equilibrium when using a force to distort the equilibrium of an object, it turns again at the original position when applying the same force but in opposite direction as before. The condition to have unstable equilibrium is
There are some examples in which objects are leaned but they still don't fall sideways. In other examples, objects start falling sideways despite they apparently seem at vertical position. As long as the vertical line drawn from the centre of gravity falls inside the lower base of the object, it doesn't fall sideways. When the object leans at such an extent that the vertical line drawn from the object's centre of gravity falls outside its lower base, the object falls sideways.
There exists a kind of classification regarding stability even within the same category of equilibrium. It is determined by the position of centre of gravity in respect to the ground. Higher the centre of gravity, less stable the object is.
In summary, the equilibrium or stability of objects depends of three factors:
Some applications of centre of mass in Physics, include:
Enjoy the "Centre of Mass. Types of Equilibrium" revision notes? People who liked the "Centre of Mass. Types of Equilibrium" revision notes found the following resources useful:
We hope you found this Physics tutorial "Centre of Mass. Types of Equilibrium" useful. If you did it would be great if you could spare the time to rate this physics tutorial (simply click on the number of stars that match your assessment of this physics learning aide) and/or share on social media, this helps us identify popular tutorials and calculators and expand our free learning resources to support our users around the world have free access to expand their knowledge of physics and other disciplines.