Daily Archives: 15 septiembre, 2016

Chapter 2. Oscillations and waves (I)

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Raymond A. Serway and John W. Jewett. “Physics for Scientists and Engineers with modern physics“, 8th edition, Brooks/Cole, Belmont, USA (2010)

Part 2. Oscillations and Mechanical Waves

We begin this part of the course by studying a special type of motion called periodic motion, the repeating motion of an object in which it continues to return to a given position after a fixed time interval. The repetitive movements of such an object are called oscillations. We will focus our attention on a special case of periodic motion called simple harmonic motion. All periodic motions can be modelled as combinations of simple harmonic motions.

Simple harmonic motion also forms the basis for our understanding of mechanical waves. Sound waves, seismic waves, waves on stretched strings, and water waves are all produced by some source of oscillation. As a sound wave travels through the air, elements of the air oscillate back and forth; as a water wave travels across a pond, elements of the water oscillate up and down and backward and forward. The motion of the elements of the medium bears a strong resemblance to the periodic motion of an oscillating pendulum or an object attached to a spring.

To explain many other phenomena in nature, we must understand the concepts of oscillations and waves. For instance, although skyscrapers and bridges appear to be rigid, they actually oscillate, something the architects and engineers who design and build them must take into account. To understand how radio and television work, we must understand the origin and nature of electromagnetic waves and how they propagate through space. Finally, much of what scientists have learned about atomic structure has come from information carried by waves. Therefore, we must first study oscillations and waves if we are to understand the concepts and theories of atomic physics.

[kml_flashembed movie="http://www.youtube.com/v/SzObC64E2Ag" width="480" height="360" wmode="transparent" /]

[kml_flashembed movie="http://www.youtube.com/v/eAXVa__XWZ8" width="480" height="360" wmode="transparent" /]

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Rules or common sense?

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The best way to learn physics is practise, practise, and practise. You need to check whether you understood all the concepts or not, therefore, try to think logically and correlate your questions with real life situations. I saw in this web-page some ideas for learning physics and other technical courses. In summary, these are some points to take it into account:

  1. Never miss a class. Ever. Although you do not believe it, you can learn physics with lectures.
  2. Never fail to do every problem of every assignment.
  3. If you are required to hand in problem solutions, do the problem twice. The first version should go in your own notebook, along with all the failed attempts. The second should be a copy to hand in.
  4. Always prepare for each class. That means have a look at what is coming up in the text or notes after you have done the assignments. Check the guide of the subject.
  5. Write out your work for every problem clearly. Show every step, even if your calculator has 128 Mb of memory.
  6. Do not ever try to erase your mistakes, just cross out with a single line.
  7. Always draw a picture for each problem and label it clearly.
  8. To study for tests, do problems. Write down any formulas each time you use them and you will know them by heart without any further effort.
  9. Always ask for help, but make sure that you have done your part before you go to the teacher. This means that you must work out the offending problem neatly up to the point where you lose the trail.
  10. All that really ever works is to review and to practise solving problems.
  11. Learn to draw a good graph, properly labelled and scaled.
  12. Always do your own work, especially in laboratory settings. That means preparing your own report on your own, even if the data was collected by someone else.
  13. Always prepare for the laboratory: know what you are going to do and how you are going to do it.
  14. Last but not least, it is important in your career to demonstrate your integrity as a student and as a person. A reputation for honesty will serve you far better than any course grade. It is incredible, isn’t?!!!!

 voltaire_quoteTherefore, student life could be easier to learn physics practising it than memorising it. I suggest to you think in physics not in mathematical equations.