- Breif summary of the project and aims
The easiest way to get a student to learn a concept is to turn it into an experience, that is, an experiment. If the experiment turns into a game to do with classmates or friends, it is even better. In the realization of this project, we set ourselves the objective of demonstrating the concept of balance of bodies. Through the use of simple experimental prototypes, we intend to make the relationship between the body and the position of its centre of gravity identifiable. It is known that a suspended or leaned body is in stable equilibrium if and only if the position of its centre of gravity is vertically aligned with the position of the point of attachment or once its minimum possible height has been reached. We thought to present some simple “homemade” demonstration prototypes that allow us to identify this property and analyse its functioning. Students, therefore, will be invited to participate in the realization of simple experiments, through which to acquire naturally the concept of the centre of gravity.
- Material and assembly (including some medium-low resolution figures, diagrams or photographs)
The aim is to prove the above theories by means of devices and/or systems made using commonly used materials (cardboard, toothpicks, cork stoppers, glue, forks, wood, small metal objects). Easy access to the materials used will allow students to easily create experimental prototypes even in a completely autonomous way, for example at home or at school. This will promote, through a self-made methodology, the understanding of the physical principle as well as the pleasure of discovery.
- Justification: Physical principles involved and their relation to technological applications.
A body is in stable equilibrium if, by shifting it slightly from its equilibrium position, it naturally tends to return to it. In fact, when all the forces acting on a body cancel each other out, the body is in equilibrium. To understand how the balance of a body works it is necessary to know its weight and its point of application, where the weight of a body indicates the force with which the body is pushed down (force of gravity).
The demonstration prototypes involved in the experiment will be free to move and through their observation it will be understood that whenever an unstabilizing activity (temporary external force) is exerted on them, they will tend to return to their stable equilibrium position, which is the position for the body with the lowest potential energy expenditure.
- Performance and Results: Observations and Measurements
Let’s look at the case of a ship sailing on the sea, it moves safely because it has a centre of gravity and the force that will keep it in stable equilibrium will be applied. Every prototype has a centre of gravity. On the basis of this hypothesis, simulations will be carried out in which it will be possible to test that, even starting from different conditions, e. g. starting positions imposed by an external operator, each prototype will return to its original stable equilibrium conditions and will continue there until an external condition (external force) acts again which will change the equilibrium of the prototype and its position. Therefore, some prototypes will oscillate in search of the equilibrium position, others will rotate until they reach it.
- Conclusions
All bodies have a natural tendency to seek the condition of stable equilibrium. Prototypes stimulate children’s intuition to understand equivalences in existing systems. For example, the prototype made with the two forks is equivalent to a two-arm scale or a construction crane, a ship oscillates on the sea as does the eccentric wooden disc until it reaches the equilibrium position. The principle that regulates the centre of gravity of the body finds considerable applications in the field of technology, everything that is made by man has a centre of gravity; for example, the comfort with which you hold a smartphone is simulated by carefully evaluating the position of its centre of gravity, its vibration system works thanks to the rapid movement of an eccentric mass in the centre of gravity.
- Bibliography
-Esercitazioni di laboratorio della Prof.ssa K. Bertazzoni e Prof. F. L. Zumbo
-Fisica dappertutto F. Bagatti, E. Corradi, A. Desco, C. Ropa, F, Tibone – Edizioni Zanichelli
-Fisica lezioni e problemi G. Ruffo, N. Lanotte – Edizioni Zanichelli
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