1. PF Contest - Win "Conquering the Physics GRE" book! Click Here to Enter
    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!

Tourqe of a sign on the wall

  1. Mar 28, 2010 #1
    1. The problem statement, all variables and given/known data

    a uniform 2kg horizontal beam is 50cm long is bolted to a wall and supports a 5kg sign. calculate the tourqe produced by the combined weight of the beam and the sign about where it is mounted to the wall.

    2. Relevant equations

    tourqe = F x Perpendicular distance

    3. The attempt at a solution

    So im using the wall as the pivot point making the distance to the centre of mass of the beam 0.25m.

    the tourqe of the beam= (9.8x2)x(0.25)
    = 4.9Nm

    The tourqe of the sign= (9.8x5)x(0.5)

    And to get the total tourqe i have added these togther to get 29.4Nm

    But my course book says the answer is 118Nm?? i know this is a pretty simple question but i cant pick up my error :confused:
  2. jcsd
  3. Mar 28, 2010 #2


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    looks like a book error, if you described the problem correctly.
  4. Mar 28, 2010 #3
    the only thing i changed from the book is that it says a light rather than a sign.. but i think it may be a book error to. This book has many errors
  5. Mar 28, 2010 #4
    Well, one error is that it is a torque :biggrin:
  6. Mar 28, 2010 #5
    you never know the book might spell it that way to??!?!!!??
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Threads - Tourqe sign wall Date
Find the frictional force between a block and a wall Thursday at 6:45 PM
How come electric potentials have different signs? Mar 2, 2018
Ray optics sign convention Jan 25, 2018
Sign hanging at angle Nov 13, 2017