Quantcast

Got Homework?

Connect with other students for help. It's a free community.

  • across
    MIT Grad Student
    Online now
  • laura*
    Helped 1,000 students
    Online now
  • Hero
    College Math Guru
    Online now

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

Yahoo!

Four rods of equal mass m each , Ab , BC , CA , DB are placed as shown. The moment of inertia of the system about B perpendicular to the plane ABC is (AB=a)

  • one year ago
  • one year ago

  • This Question is Closed
  1. Yahoo!
    Best Response
    You've already chosen the best response.
    Medals 0

    |dw:1360169550988:dw|

    • one year ago
  2. Yahoo!
    Best Response
    You've already chosen the best response.
    Medals 0

    @JamesJ

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

    Obviously break down the problem rod by rod.

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

    And if you're really stuck, you're just going to integrate rod by rod.

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

    I (BC) = ma^2/6 ryt ?

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

    Its basically a maths ques, you just need to find rod lengths, after doing that you just have to calculate moment of inertia of each rod about B and add all

    • one year ago
  7. Yahoo!
    Best Response
    You've already chosen the best response.
    Medals 0

    Yup . i Have Calculated the length of rods BC = a/sqrt(2) , AC = a/sqrt(2) , DB = (sqrt2) * a / sqrt3

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

    I (BC) = ma^2/6 ryt ?

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

    yep

    • one year ago
  10. Yahoo!
    Best Response
    You've already chosen the best response.
    Medals 0

    I (DB) = ma^2/18 ?

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

    won' that be (2/9)ma^2

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

    Hw ?

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

    |dw:1360246728479:dw|

    • one year ago
  14. Yahoo!
    Best Response
    You've already chosen the best response.
    Medals 0

    I (DB) = M L^2 / 3 * sin^2 30 ryt ?

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

    why sin ?

    • one year ago
  16. Yahoo!
    Best Response
    You've already chosen the best response.
    Medals 0

    |dw:1360246891927:dw|

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

    I don;t think angle matters

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

    For calculation of I,

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

    Because the axis is perpendicular to plane, the rod will make 90 degrees with the axis, doesn't matter how it is placed.

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

    Do you have the final ans ?

    • one year ago
  21. Yahoo!
    Best Response
    You've already chosen the best response.
    Medals 0

    Yup 25 M a^2 / 18

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

    <Lets see if we get that by my method>

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

    So DB = 2M a^2 /9

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

    And AC = ma^2/6 + 3ma^2/6 = 2ma^2 /3

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

    So sum = ma^2 (2/3 + 2/9 + 1/6) = 19/18ma^2

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

    hmm, okay doesn't match

    • one year ago
  27. Yahoo!
    Best Response
    You've already chosen the best response.
    Medals 0

    i think that angle matters

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

    Wait I missed AB

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

    AB = ma^2 /3 Sum = 25/18

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

    Got it! B|

    • one year ago
  31. Yahoo!
    Best Response
    You've already chosen the best response.
    Medals 0

    But Hw Did u Claculate I (AC) ??

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

    calculate about C, then B

    • one year ago
  33. Yahoo!
    Best Response
    You've already chosen the best response.
    Medals 0

    Ok...got it....:)

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

    "Angle will not matter here" ;)

    • one year ago
    • Attachments:

See more questions >>>

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.