A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

anonymous

  • one year ago

Setting up a differential equation? Attachment below~

  • This Question is Closed
  1. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I am sure I have.. or am going the wrong direction. How do I create a differential equation from the following data?

    1 Attachment
  2. IrishBoy123
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    without knowing the details, you're missing an R on the friction term and the signs are wrong [though they do correct themselves in the second line....] :p

  3. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I am trying to do this from formulas, and have trouble finding ... the relevant formulas :x

  4. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I managed to do this without any fraction (no dampening) using the ...Force moment formula \[-mglsin(\phi) = I_0\frac{ d^2\phi }{ dt^2 }\] where I is \[I_0 = mR^2\]

  5. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    However, I am not sure how to... apply this with a friction :s

  6. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Appreciate your help - Physics section is very inactive compared to the math section :)

  7. IrishBoy123
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    think you might wish to explain the physical situation/context eg post/link the original question in meanwhile, and guessing the situation, around the centre of rotation \(mR^2 \, \ddot \theta = - mg \sin \theta \, \cdot R+ \mu mg \cos \theta \, \cdot R\) at this point, normally, you would linearise, \(\lim\limits_{\theta \to 0} \sin \theta \approx \theta\) \(\lim\limits_{\theta \to 0} \cos \theta \approx 1\) that would leave you with \( \, \ddot \theta + {g \over R} \theta = {g \over R} \mu \)

  8. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Hmm... I don't understand why there is an R - I mean, if you decom.. dec... move it around I dont get an R - do the R has something to do because its going in a circular motion?

  9. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    If we only look at one of them - for example the µmg*cos(phi)*R. How do we... get to that? Especially with the R @IrishBoy123

  10. IrishBoy123
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    it would great make sense to post the actual physical question, if you have one. you say friction plays a role here, but as this looks like a simple pendulum problem [\(\ddot \theta = - k \theta\)], i have responded on the basis there is some physical aspect that means you can just add in a frictional force ......which you can, without it having any real physical meaning...... but it would still make a lot more sense to be talking about a concrete example.

  11. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    If I translate the text (roughly); ------ A point shaped pendel sliding on a surface. The surface is on pair with a circle and has radius 1m. Draw a figure, write all the relevant forces and formulas and calculate your way to a differential equation

  12. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Appreciate the help - Going to work more on this

  13. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.