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I Work/Energy in the introduction to dynamics

  1. Apr 5, 2017 #1
    An introductory course in rigid body dynamics for mechanical engineers introduces kinematics, then kinetis and then work/energy.

    Can I ask for your opinions?

    Is this necessary?

    I can see the need to discuss work/energy to understand Hamilton's Principle.

    But is there any reason to labor students with this topic and to the extent it is currently taught in most introductory textbooks?

    As I see it, the Work/Energy/Potential Energy topic is good for cases where there is little to no dissipation. And it allows for rapid back-of-envelope checking of solutions.

    But in the current pedagogy, it seems disordanatly elevated. And as a result, students see it as a whimsical alternative to getting equations (and do lots of roller coaster problems).

    Yes, it is important to introduce the terms. But I have only really learned it when studying differential forms. It seems we waste too much time teaching work/enegy in the undergraduate curriculum, when they really need to understand how to extract equations of motion. Once the students get to the real world, they never use Work/energy solutions, excpet insofar as Hamilton's Principle, etc.

    May I ask for your opinions on this?

    (And, yes, I appear to be contradicting myself, esp. with regard to my other question on virutal work.... so be it.)
    Last edited: Apr 5, 2017
  2. jcsd
  3. Apr 5, 2017 #2

    jack action

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    The concept of conservation of energy is well known but really difficult to grasp for most people. Probably because it is too abstract (say compared to conservation of mass). So I don't think you can talk about it too much.

    The best example I can think of are the endless discussions about what is more important for vehicle performance: Engine power or torque? When you fully grasp the concept of conservation of energy, this is a no brainer. But start that discussion with students in mechanical engineering and you won't hear the end of it.

    You need to learn more than blindly follow mathematical procedures. You need to fully understand the guiding principles behind those equations.
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