Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Statics: Equilibrium of Machines

  1. Oct 22, 2005 #1
    The problem is stated in the picture. And I drew the FBDs of the top half of the bolt cutter, as shown in the second page:

    Setting moment about A to be 0, I obtain -Q(1 in)-FBy*4 in=0
    And By= -Q/4 lb

    Then setting moment about C to be zero. I obtain
    FBy(0.5 in)-20 in(75 lb)=0
    Substitute in By, I get the magnitude of Q to be 12000 lb.

    http://img368.imageshack.us/img368/7535/1239zw.jpg [Broken]
    http://img368.imageshack.us/img368/431/22cm.jpg [Broken]

    Am I correct?

    Attached Files:

    • 2.jpg
      File size:
      54.6 KB
    • 123.jpg
      File size:
      46.5 KB
    Last edited by a moderator: May 2, 2017
  2. jcsd
  3. Oct 22, 2005 #2


    User Avatar
    Homework Helper

    What was the problem then?, it looks good to me (the procedure, i didn't do the arithmetic).
  4. Oct 23, 2005 #3
    The problem just seems...too easy...
  5. Oct 23, 2005 #4


    User Avatar
    Homework Helper

    I was checking the problem again you forgot the Bx component when you did moment about C, it does have a moment, and the lever arm for 75 about c is 19.5
  6. Oct 27, 2005 #5
    AE is 2-force member (so the reaction at A is only Ay), so that Bx is actually zero (due to the equilibrium eqs of AB). Then you can solve the rest of them.
    Last edited: Oct 27, 2005
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook