1. Not finding help here? Sign up for a free 30min 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!

Moments Question

  1. Jan 8, 2017 #1
    1. The problem statement, all variables and given/known data

    A uniform ladder 5m long and of mass 40kg rests with its upper end against a smooth vertical wall and with its lower end 3m from the wall on rough ground. Find the magnitude and direction of the force exerted at the bottom of the ladder. (G=9.81ms^-2)

    2. Relevant equations
    ACM=CM
    moment=force x distance from the pivot
    3. The attempt at a solution

    w(moment) = (40 x 9.81) x 2.5 =981 Nm clockwise

    ACM=CM

    therefore: reaction moment = 981Nm
    and force = 981/3 =327N anticlockwise

    Is this right or am i very far off??
     
  2. jcsd
  3. Jan 8, 2017 #2

    Orodruin

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Gold Member

    This is not correct. It should be moment = force x moment arm. The moment arm is equal to the distance from the pivot only if the force is orthogonal to the separation from the pivot.

    What is the moment arm of the gravitational force?
     
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: Moments Question
  1. Question on moment (Replies: 12)

  2. Moments question (Replies: 3)

  3. Moments question (Replies: 7)

  4. Moments question (Replies: 1)

Loading...