Archimedes, the Center of Gravity, and the First Law of Mechanics: The Law of the Lever
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|Author||Andre K T Assis|
This is the second edition of a book originally published in 2008.
One of the goals of this book is to present the basic phenomena of mechanics through simple experiments performed with inexpensive materials. We present the fundamental experiments on falling bodies, equilibrium and oscillations around equilibrium positions. We also show how the theoretical concepts are formed and modified during this process, just as occurred in the formulation of the basic laws of mechanics.
We show how more complex phenomena can be explained and clarified by means of elementary experiments. Playful and curious experiments are also presented. They stimulate creativity, critical thinking and a sense of humour in science. They also relate everyday phenomena to the fundamental laws of physics.
The emphasis is placed on experimental activities. After the experiments we formulate the definitions, concepts, postulates, principles, and laws describing the phenomena. The materials utilized are very simple, easily found at home or in stores, all of them very inexpensive. Even so, we can carry out very precise experiments and construct sensitive scientific equipment. The reader need not depend on any school or research laboratory, as he can build his own equipment and perform all the measurements.
If the experiments presented here are performed in the classroom, each student should ideally perform all the tasks, even when working in a group. Each one should build his own equipment (support, plumb line, lever, etc.), cut out his geometric figures and then take all this personal material home. This procedure is richer in lessons than simple demonstrations of the effects by a teacher. It is essential that all students put their hands to the plough.
The book is also rich in historical information, which gives the context in which some laws were discovered, and also different approaches taken in discovering them. We are careful about in formulating concepts and physical principles. It will be seen, for example, how difficult is to find the correct words to precisely define the center of gravity so that this concept can encompass a whole series of experiments. We distinguish clearly between definitions, postulates, experimental results, and physical laws. We also distinguish explanations from descriptions of phenomena. These aspects illustrate the sociological and human aspects of the formulation of physical laws.
This book is written for students and teachers of science, physics, and mathematics. It can be utilized at High Schools or at Universities, depending on the level at which each aspect is analyzed and explored. It has enough experimental and theoretical material to be employed in all levels of teaching. Each teacher should adapt the contents presented here to his own school environment. It can also be utilized in courses on the history and philosophy of science.
The best way to grasp the contents of the book is to perform the majority of the experiments described here in parallel with the reading. There are many philosophical, theoretical, and mathematical approaches relating to physical science. But physics is essentially an experimental science. It is the combination of all these aspects that make it so fascinating. For this reason we strongly recommend that the experiments presented in the book be repeated and improved. We hope that the reader will have the same pleasure in performing these experiments as we had in developing them.