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Homework Help: A Pickup Truck and a bit of Friction

  1. Sep 23, 2008 #1
    1. The problem statement, all variables and given/known data

    A pickup truck with a steel bed is carrying a steel file cabinet. If the truck's speed is 27 m/s, what is the shortest distance (m) in which it can stop without the file cabinet sliding? (Use µs = 0.8 for the coefficient of static friction of steel on steel.)

    2. Relevant equations

    F=ma

    3. The attempt at a solution

    Well, to start I made a force diagram and concluded that, as usual, the normal force equals the weight. That only leaves me to worry about the x-axis, the push speed and the friction. But, I'm not sure where to go and I don't remember how to convert velocity into force since velocity isnt' a force. And I can't find the acceleration. Thank you in advance for any help and/or hints!

    ~Bachi
     
  2. jcsd
  3. Sep 23, 2008 #2

    tiny-tim

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    Welcome to PF!

    Hi Bachi! Welcome to PF! :smile:

    Hint: first, use your F = ma to find how much acceleration is needed to make the cabinet slide (you don't need velocity for this part).

    Then use that acceleration to find the stopping distance. :smile:
     
  4. Sep 23, 2008 #3
    Thank you for your welcome =)

    How would you use F = ma to find the acceleration when you don't have the mass?
     
  5. Sep 23, 2008 #4

    tiny-tim

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    Hi Bachi234! :smile:

    Just call the mass m, and write out the equations …

    you'll find that everything has an m in it (like mg), and you can just divide by m. :wink:

    Have a go! :smile:
     
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