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Calculate the work done by the mover

  1. Apr 7, 2007 #1
    1. The problem statement, all variables and given/known data
    A mover pushes a 85kg crate along the floor at a constant speed through a displacement of 3,1m[E]. The coefficient of kinetic friction between the floor and crate is 0.22.
    A) Calculate Fn and Fapp.
    B] Calculate the work done by the mover.


    3. The attempt at a solution
    Fg=mg
    =85kg*9.8N/kg
    Fg=833N
    So Fn=Fg
    but how can i find Fapp

    B] w=183N*3.1m
    w=567.3
     
    Last edited: Apr 7, 2007
  2. jcsd
  3. Apr 7, 2007 #2

    daniel_i_l

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    The box is moving at a constant speed, what does that say about the sum of the forces on the box?
     
  4. Apr 7, 2007 #3
    plz helpp.............
     
  5. Apr 7, 2007 #4

    arildno

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    What does the word constant mean??
     
  6. Apr 7, 2007 #5
    not changing
     
  7. Apr 7, 2007 #6

    daniel_i_l

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    Yes, so what is the acceleration of the box? How can you use that to find the sum of all the forces?
     
  8. Apr 7, 2007 #7
    So a=0
    Fnet=0
    Fnet=Fapp+Ff
    Fapp=0-180
    Fapp=180
    is that right?
     
    Last edited: Apr 7, 2007
  9. Apr 7, 2007 #8
    [tex]Given[/tex]

    [tex]m=0.2kg[/tex]
    [tex]\Delta {h}_{1}=0.835m[/tex]
    [tex]{v}_{1}=0m/s[/tex]

    [tex]Required[/tex]

    [tex]{E}_{g} and {E}_{k}[/tex]

    [tex]Solution[/tex]

    [tex]{E}_{g}={m}g\Delta h[/tex]
    [tex]={0.2kg}*9.8N/kg*0.835m[/tex]
    [tex]{E}_{g}=1.63J[/tex]


    [tex]{E}_{k}=(1/2)m{v}_{1}^2[/tex]
    [tex] =(1/2)0.2Kg(0m/s)^2[/tex]
    [tex]{E}_{k}=0J[/tex]

    [tex]{E}_{T}=1.56J[/tex]
     
    Last edited: Apr 8, 2007
  10. Apr 7, 2007 #9
    no response
     
  11. Apr 7, 2007 #10

    arildno

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    Where did you get the 180 from, and why did you cut out the sign in front of it?
     
  12. Apr 7, 2007 #11

    Hootenanny

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    Your working seems ok, but I don't know where you got 180 from. Check your math...

    Edit: Dammit, thats three times thats happened today :grumpy:
     
  13. Apr 7, 2007 #12
    soory i mean 183
     
  14. Apr 7, 2007 #13

    arildno

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    I couldn't care less if the number was 54 or square root of pi fifths.

    I want you to tell us:

    1. HOW did you arrive at that number??

    2. WHY did you take away the sign?
     
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