A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

anonymous

  • one year ago

A block and tackle is used to raise a 72.0 N crate 12.3 m from the loading dock to the ship. This requires a force of 25.0 N to be applied by the longshoreman. Part 1: What is the mechanical advantage of the block and tackle? Part 2: How much rope must be pulled? Note: Assume that IMA = MA. Part 3: The longshoremen have only a 40 m rope that they are told not to cut. They use this for the block and tackle. How does this affect the efficiency of the block and tackle? **how do we solve these? :/ thanks @Michele_Laino !!:)

  • This Question is Closed
  1. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    part 1 the requested advantage is given by the subsequent ratio: \[\large R = \frac{{72}}{{25}}\]

  2. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    oh okay! so we get 2.88 is the requested mechanical advantage?

  3. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    yes! Whereas the efficiency E, of our machine, is: \[\Large E = \frac{{25}}{{72}} = ...\]

  4. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    ohh okay! it is 0.347222....

  5. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    no, it is an additional information only. Our answer, to part 1 is 2.88

  6. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    oh ok! so we do not need to include the efficiency? just the 2.88 mechanical advantage?

  7. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    yes!

  8. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    okie! so onto part 2!

  9. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    for part #2, if I call with L the length of the pulled rope, then we can write: \[\large 72 \times 12.3 = 25 \times L\]

  10. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    so we have: \[\Large L = \frac{{72 \times 12.3}}{{25}} = ...meters\]

  11. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    we get 35.424!

  12. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    correct!

  13. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    so is that the amount of how much rope must be pulled? 35.424 m?

  14. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    yes!

  15. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    ok! yay!! so onto part 3?

  16. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    if we have to pull 40 meters of rope, then the force F applied by the longshoremen, is: \[\Large F = \frac{{72 \times 12.3}}{{40}} = ...Newtons\]

  17. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    ok! so we get 22.14 Newtons! is that our solution for part 3?

  18. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    oh wait, that is just the force, right? how can we find the efficiency?

  19. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    the new advantage is: \[\Large R = \frac{{72}}{{22.14}} = ...\]

  20. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    or how can we find how it affects the efficiency?

  21. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    whereas the new efficiency, is: \[\Large E = \frac{{22.14}}{{72}} = ...\]

  22. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    I think that your problem asks for efficiency, also in part #1

  23. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    ok! so we get 0.3075 is the efficiency? and i think we don't need it for part 1? since it asks for mechanical advantage only? or do we need to include the efficiency we calculated earlier for part 1?

  24. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    so the answer to part #1 is: \[\Large E = \frac{{25}}{{72}} \cong 0.35\]

  25. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    that's right! the new efficiency is: \[\Large E = \frac{{22.14}}{{72}} \cong 0.31\]

  26. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    namely the efficiency will decrease

  27. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yes:) and yay!! so that is how it affects efficiency? it will decrease?

  28. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    yes! correct!

  29. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yay! thanks!! so we are done?

  30. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    yes! we have finished!

  31. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yay!! ok! onto the next!!:)

  32. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    thank you!!

  33. Michele_Laino
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    :) :)

  34. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.