Skip to content

14 Comments

  1. Peter Niemann
    June 6, 2018 @ 4:59 am

    7 to 1

  2. Tom Kiley
    June 6, 2018 @ 1:31 pm

    12:1

  3. stan gibbs
    June 7, 2018 @ 6:52 am

    6-1

  4. Jesse
    June 7, 2018 @ 7:12 am

    Looks like a 7:1 with a change of direction. Hard to see how it’s rigged.

  5. Tom Garner
    June 7, 2018 @ 7:18 am

    12:1

  6. Jaime Torres
    June 7, 2018 @ 8:09 am

    The purchase advantage on the block set the gentleman is holding is 7 to 1. She is pulling on the carabiner he is holding with a 7 to 1 advantage. Because she is on a “frictionless” skateboard, she is just acting as a connector between the gentleman and the block set.

    She neither loses nor gains advantage because of that connection.

    its as if was the man pulling in t he working end of the rope. He feels the 1/7th of the load on his left hand as he feels on his right hand (excluding drag, friction, and all the other incalculables)

  7. paul
    June 7, 2018 @ 8:11 am

    7

  8. Frank Ficken
    June 7, 2018 @ 10:20 am

    Because she is on the moving board, she really doesn’t exert any force except what comes from holding your hand, essentially, you’re pulling on the line yourself. It’s a bit hard to see all the lines on the blocks in front of you, but it looks like a 1:7 advantage.

  9. mike
    June 7, 2018 @ 11:23 am

    None to none.

  10. Nathan Bossett
    June 7, 2018 @ 3:27 pm

    7:2
    Say each arm is pulling 1 lb.
    Guy feels 1 lb from arm + 6 lb from block, total 7
    Woman is pulling with 2 lb (woman+skateboard are needless complications: you could have two 1 lb hanging weights with blocks to make the force horizontal and the mechanical situation would be the same.

    • Nathan Bossett
      June 7, 2018 @ 3:29 pm

      Oh. I see it says to leave the answer in comments below, but then it says not to post the answer online. Confusing…. this is online.

  11. Peter Hennessey
    June 8, 2018 @ 4:15 pm

    Ok, starting with a six part purchase rove to advantage with a turning block, that give 7-1 advantage, plus one more part in the handhold, in my book that makes 8 to 1 advantage, and a lot of fun judging by her smile!

    • Peter Hennessey
      June 9, 2018 @ 2:22 pm

      P.S. The fact she’s standing on a moving platform serves to elimnate any out of balance forces, making the pull on each hand equal and opposite. So, 7/1 in the left hand plus 1/1 in the right hand equals 8/1. QED.

  12. Not Falling Far, Part 3: The Ascender – Brion Toss Yacht Riggers
    September 4, 2018 @ 8:20 am

    […] and our most recent puzzle, Recirculating Purchase, got more than twice as many hits as our previous one-day record. If you are looking for a good […]