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Quick question about work

  1. Nov 28, 2014 #1
    [Note by mentor: This thread does not use the homework template because it was moved here from a non-homework forum.]

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    Okay i've issue related to work so i thought i should ask here. Its really frustrating I've tried everything but I just can't figure out how to find work.
    Question:
    A set of frictionless wheels are attached to the bottom of a box, which is then measured and found to have a mass of 6.0kg. The box is placed on the floor, and a student of Physics uses a brief horizontal force of 150N to push the box sideways, after which the box rolls across the floor with constant velocity. How much Work does the floor do on the box as it rolls along?

    since work is w= fxd and there is no distance given. also that to find a distance you need time and there is no time given either. I can't figure out how to do it, any ideas please? thanks
     
    Last edited by a moderator: Nov 28, 2014
  2. jcsd
  3. Nov 28, 2014 #2

    A.T.

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    What is the value of f? Do you really need d in this case?
     
  4. Nov 28, 2014 #3
    f is Force and work is force x distance so yes I need it. I can't think of else way
    I tried other formula too which is Work = 1/2mv^2 but velocity is constant has no value so no idea.
     
  5. Nov 28, 2014 #4

    russ_watters

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    If there is no force being applied, there is no work...so why do you need the distance it rolls without a force?
     
  6. Nov 28, 2014 #5
    150 N Force is being applied, it says in the Question
     
  7. Nov 28, 2014 #6

    A.T.

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    By what?
     
  8. Nov 28, 2014 #7
    By a student of physics who is pushing it horizontally
     
  9. Nov 28, 2014 #8

    russ_watters

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    But that isn't the force that the question asks about.
     
  10. Nov 28, 2014 #9
    so you are saying that there is no work done because there is actually no force acting on it?
     
  11. Nov 28, 2014 #10

    A.T.

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    What does the formula for work say if f=0?
     
  12. Nov 28, 2014 #11
    If force is zero work would be zero too becase formaul is force x distance. but in question its implying that work happened as box moved
     
  13. Nov 28, 2014 #12

    A.T.

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    You have to read more carefully what it says/asks. It asks about work by floor, not by the student.
     
  14. Nov 28, 2014 #13
    Frictionless means there is no friction force, right?
     
  15. Nov 28, 2014 #14
    Yup i figured that and I must admit that I was being stupid and I didn't read the last words properly that work done by "floor" which is doing nothing cuz wheels are frictionless.
    ahhh not a good feeling. no.
    thanks mate.
     
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