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!

How far is the center of mass from the handle end of the club-axe?

  1. Oct 8, 2008 #1
    1. The problem statement, all variables and given/known data

    A club-axe consists of a symmetrical 11.0 kg stone attached to the end of a uniform 2.9 kg stick, as shown in the figure. The length of the handle is L1 = 93.0 cm and the length of the stone is L2 = 10.0 cm. How far is the center of mass from the handle end of the club-axe?

    2. Relevant equations



    3. The attempt at a solution[/b
    I'm not sure how to do this, I can up with 58.9cm on my own but most likely not the correct way, any help appreciated!
     
  2. jcsd
  3. Oct 8, 2008 #2

    LowlyPion

    User Avatar
    Homework Helper



    How much do they weigh together?
    Won't half the weight be on each side at the balance point?

    Starting from the end with the stone, how much does the weight of the stone increase the weight to it's side of the balance point on a per cm basis? If the stick passes through the stone, how much does the stick add per cm? Now all you have to do is divide that into half the total weight to give you where it balances.
     
  4. Oct 8, 2008 #3
    I believe that's what I have done. Do you come up with 58.9 cm?
     
  5. Oct 8, 2008 #4

    LowlyPion

    User Avatar
    Homework Helper

    How is that answer possible?

    The balance point must lie within the stone as it is 4 times heavier than the whole stick.
     
  6. Oct 8, 2008 #5
    Ok the stone weighs 1.1kg/cm and the stick is 1.1 kg/35.279cm. Is this what you are talking about?
     
  7. Oct 8, 2008 #6

    LowlyPion

    User Avatar
    Homework Helper

    So no, you should deal with the center of mass of the stone.

    Where is the stone? Added to the end? Or is the stick through the middle?
     
    Last edited: Oct 8, 2008
  8. Oct 8, 2008 #7
    I got it (46.5x2.9+98x11)/(2.9+11), the stone is just added on.
     
  9. Oct 8, 2008 #8

    LowlyPion

    User Avatar
    Homework Helper

    OK. Sorry, my first post was a little misleading.

    What you are balancing then is something on the left (the stone end) that looks like

    1.1*(10 - x)/2 the center of mass times the moment arm that equals
    1.1*x/2 +2.9*(x+46.5)

    So the total from the handle end is 93 + x.
     
  10. Oct 8, 2008 #9
    the center of mass is at 87.26cm from the end of the stick and lon-capa accepted it.
     
  11. Oct 8, 2008 #10

    LowlyPion

    User Avatar
    Homework Helper

    OK. So the stick goes to the end of the stone. Not the stone at the end of the stick.

    Sounds about right then.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: How far is the center of mass from the handle end of the club-axe?
Loading...