1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Mechanical principles rotating systems

  1. May 13, 2015 #1
    1. The problem statement, all variables and given/known data
    A shaft 2 m long rotates at 1500 revs min–1 between bearings as
    shown in FIGURE 2. The bearings experience forces of 5 kN and
    3 kN acting in the same plane as shown. A single mass is to be used
    to balance the shaft, so that the reactions are zero. The mass is to be
    placed at a radius of 200 mm from the shaft centre, 180° from the
    direction of the bearing reactions. Determine the size and position (a
    and b) of the mass to be used.

    HNCPic1.jpg

    (b) The shaft in part (a) is to be balanced using two masses (m1 and m2)
    placed 0.5 m and 1.5 m from end A and 180° from the direction of
    the bearing reactions, each on radius arms 100 mm long. Calculate
    the sizes of m1 and m2.




    2. Relevant equations
    F=mrω^2

    up forces must equal down to be in equilibrium

    3. The attempt at a solution
    It is B) that I am confused about

    Do you need to use some sort of simultaneous equation to work out any of the two masses ? I have tried using the balancing equating but I cant seem to get the correct answer
     
  2. jcsd
  3. May 13, 2015 #2

    SteamKing

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    Sorry, the attached figure doesn't appear in your post. :frown:

    If you have an attempted solution to the problem, please post it.
     
  4. May 13, 2015 #3
    5000N x 2m - ((m1 x .1m x157^2)x1.5) - ((m2 x .1m x 157^2)x0.5m) =0
    10,000 - (m1 x 3697.35) + (m2x1232.45)=0
    10000/(3697.35+1232.45)=m1+m2
    2.028= m1+m2

    Pretty sure this is wrong to be honest but not sure where to go from here or what approach I should be making

    Thanks
     
  5. May 13, 2015 #4

    SteamKing

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    Any word on the figure missing from the OP? That would be a big help to anyone trying to guide you.
     
  6. May 13, 2015 #5
    Sorry yes there you go
     

    Attached Files:

  7. May 13, 2015 #6

    SteamKing

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    This is a better view:

    image-shaft.jpg
    Along with your calculations:
     
  8. May 13, 2015 #7
    No problem, do u think that is on the right lines or way off?
     
  9. May 13, 2015 #8

    SteamKing

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    I haven't had a chance to look at it. If someone else has any suggestions, please feel free to dive in. :smile:
     
  10. May 13, 2015 #9
    No problem cheers
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Mechanical principles rotating systems
  1. Mechanical Principles (Replies: 4)

Loading...