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Finding support reaction

  1. Oct 14, 2016 #1
    1. The problem statement, all variables and given/known data
    I'm asked to find the VA and VB in this question .

    2. Relevant equations


    3. The attempt at a solution
    Here's my working :
    VA +VB =1000(6) =5000+0.5(400x3)
    VA +VB = 11600

    total moment about A = 0 , sum of moment about A = 5000(6) -9000 + (4000/2)(9 +3(2/3) ) -VB(9) =0
    hence VB = 9667N pointed upwards

    total moment about B = 0 , sum of moment about B = 1000(6)(9) -VA(9) +9000+5000(3)-4000(3/2)(2) = 0
    VA = 7333N (upwards)

    But , the ans provided is VA = 8000N , VB = 9000N , which part i did wrongly ?

     

    Attached Files:

  2. jcsd
  3. Oct 14, 2016 #2

    CWatters

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    Is that meant to read VA + VB = 1000(6) + 5000 + 0.5(400*3) ?

    If so then..
    Where does the 6 come from?
    Where does the 400 come from?
     
  4. Oct 14, 2016 #3
    sorry , i made a mistake , it should be VA + VB = 1000(6) + 5000 + 0.5(4000x 3) =17000N ....
     
  5. Oct 14, 2016 #4

    CWatters

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    and the 6?
     
  6. Oct 14, 2016 #5
    The 1000 N /m has 6 m
     
  7. Oct 14, 2016 #6

    CWatters

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    Ok yes I agree. 1000N/M for 6m.
     
  8. Oct 14, 2016 #7

    CWatters

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    Ill try and have a look at the rest tomorrow.
     
  9. Oct 15, 2016 #8

    CWatters

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    The centre of mass of the "triangular load" is 1/3rd of the base from it's left hand edge not 2/3rds so it should be..

    5000(6) -9000 + (4000/2)(9 +3(1/3) ) -VB(9) = 0
     
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