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!

Mass of dresser?

  1. Apr 1, 2016 #1
    1. The problem statement, all variables and given/known data
    "Using the pulley system shown to lift the heavy dresser, the person is applying a force of 150N to the end of the rope. Which of the following is closest to the maximum mass of the dresser that can be lifted with this force? [Ignore weight & friction from pulleys/rope.]"

    A) 46kg
    B) 92kg
    C) 110kg
    D) 150kg
    E) 180kg

    20160401_203844~2[1].jpg 2. Relevant equations

    Newton's 2nd & 3rd laws

    3. The attempt at a solution
    So she's pulling with 150 N and there are three pulleys connected to the dresser, so her effort is tripled. 450N lifts the dresser and so the mass is 46kg?
     
  2. jcsd
  3. Apr 1, 2016 #2

    gneill

    User Avatar

    Staff: Mentor

    Label each section of the rope with its tension. How many sections of rope are supporting the dresser?
     
  4. Apr 1, 2016 #3
    I count six sections plus the one the girl is holding so seven. 7*150 divided by g gives approximately 110kg?
     
  5. Apr 1, 2016 #4

    gneill

    User Avatar

    Staff: Mentor

    The one the girl is holding is holding the girl...not the dresser. So one less. You want to count only the ropes that are directly supporting the load.
     
  6. Apr 1, 2016 #5
    Ah so six. And the answer is 92kg?
     
  7. Apr 1, 2016 #6

    gneill

    User Avatar

    Staff: Mentor

    Yes.
     
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: Mass of dresser?
  1. Sliding dresser (Replies: 9)

  2. Mass on Mass with Mass (Replies: 6)

  3. CENTRE OF MASS (Replies: 2)

Loading...