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Studying Trying to Understand Rotational Motion

  1. Feb 6, 2017 #1
    I am really troubling to understand the rotational motion concept.Like angular accceleration,angular velocity torque ext.I dont know, I listened my professor's video lectures, I looked some online course pdfs but I need to learn the basics and I need more basic practice for simple understanding .

    Any advice ?

    Thanks
     
  2. jcsd
  3. Feb 6, 2017 #2

    ZapperZ

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    What you are describing is rather vague. If we give you "advice", how are we to know if this is something that you had encountered already and, obviously, is not working.

    What you should do is pick out ONE example of a problem that you cannot solve, go to the Homework forum and show what you have done, and then indicate where you got stuck. Then wait for help or queries from other members here.

    Once it is solved, see if you've understood why you got stuck, and if you've understood something that you didn't before. Go find another similar problem, and try solving it. If you can, there's a good chance that you've overcome this obstacle. If not, then repeat the above.

    Otherwise, we are left with some vague idea that you have problems in rotational dynamics without really any specific information on what really is the source of the issue.

    Zz.
     
  4. Feb 6, 2017 #3

    ehild

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    https://en.wikipedia.org/wiki/Rotation_around_a_fixed_axis

    Scroll down to "equations of kinematics"
     
  5. Feb 6, 2017 #4
    Well you are right.I know the all equations.Just putting them together and base them on a logic is much more harder to me for this subject (I dont know why )
     
  6. Feb 6, 2017 #5
  7. Feb 6, 2017 #6

    ehild

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    Look at the data. Given are the initial angular velocity, ωi=1.5 rad/s2, and the final one, ωf=0 as the wheel stops. The angular displacement is also given, θ=80π. You find the relation among the kinematic equations
    upload_2017-2-7_5-35-15.png .
    Substitute the given data and solve for t.
     
  8. Feb 7, 2017 #7
    I am trying to solve the problems on my book but going terrible..I cant do..And I cant ask here one by one-takes too much time
     
  9. Feb 7, 2017 #8

    ZapperZ

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    Then how are you going to learn?

    You don't seem to understand what I have told you. Go to the HW forum, and ask JUST ONE question first. Try to understand where you got stuck, and how to unstuck yourself.

    Then, there is a good chance that, if things click, you will learn something by solving that problem. See if you can apply that understanding to another problem. In other words, while you may have a lot of problem you can't solve now, maybe that number will be reduced AFTER you understand how to do one.

    Besides, rotational dynamics is no different than the linear dynamics problem. If you can solve the latter, there is no reason not to be able to solve the former. The concept is the same, and the equations are similar!

    Zz.
     
  10. Feb 7, 2017 #9
    Yeah right,I can solve kinematics easily but rotational kinematics comes so hard.Maybe cause of my native language,maybe I dont fully understand the questions.Ok I ll ask now
     
  11. Feb 7, 2017 #10

    ZapperZ

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    Then you are not seeing it.

    This is a scan of what I have written on the white board in my class to drill into the students that rotational motion is no different than linear motion.

    IMG_4336.JPG
    If you can do linear motion problems, but you can't do rotational motion problems, then you need to figure out why you are having problems here.

    Zz.
     
  12. Feb 7, 2017 #11
    I know they look all the same..I really dont know where I am doing wrong.Thanks :)
     
  13. Feb 7, 2017 #12
    I guess I understand.In kinematics its simple,m/s m/s^2 thats all. Here,rad/sec rad/min rev/s rev/min and sometimes theres angels sometimes f sometimes we convert that w and makes me confused everytime
     
  14. Feb 7, 2017 #13
  15. Feb 8, 2017 #14
    I looked my book once more and I can do most of the questions now,just amazing
     
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