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Net Force of wagon

  1. Dec 17, 2006 #1
    1. The problem statement, all variables and given/known data
    A wagon with a weight of 300 N is accelerated across a level surface at .5 m/s2. What net force acts on the wagon? (g=9.81 m/s2)

    2. Relevant equations

    f=ma

    3. The attempt at a solution

    well the answer is 15 N, but I don't know how to get there. I need a little guide, because I have no clue on what to do.
    do I have to convert the 300 N into something else? eek please help me out, I'm really really lost.
     
  2. jcsd
  3. Dec 17, 2006 #2

    cristo

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    300N is a force (or the weight of the truck) In order to use F=ma, you need to convert the weight into a mass
     
  4. Dec 17, 2006 #3

    cepheid

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    Okay, first of all, I would say that if it isn't already obvious, then you should start with Newton's second law. The net force acting on an object is equal to its mass times its acceleration. Why? Well, you have the object's acceleration, and, althought you may not know it, you have the object's mass (implicitly). You are asked for the net force.

    Summary:

    F = ma

    Already given:

    a = 0.5 m/s^2

    m = ___________

    So you can see that you have all the information required to solve the problem, provided you can determine the object's mass, which should be trivial.
     
  5. Dec 17, 2006 #4
    wow I'm sorry I feel so not all here... but you find mass how?
    I mean how do I convert the weight into mass?
    eek, I'm sorry I'm really trying right now, but I can't get it. wow.
     
  6. Dec 17, 2006 #5
    never mind! I got it! yay. haha so sorry and thank y'all soo much.
     
  7. Dec 17, 2006 #6

    cepheid

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    Obviously you need to know the relationship between an object's weight, and its mass. In other words, given an object of a certain mass, (on earth), then with how much force does gravity pull down on it? This is what is represented by the quantity g.

    Intuitively you know that weight and mass are related. In a *given* gravitational field, the more massive an object, the heavier it is. You also know HOW they are related.
     
  8. Dec 17, 2006 #7
    mhm. yeah I remember now, sorry. I don't have it in my notes.... for some reason, but gosh I feel much better, because I understand it. thanks a bunch.
     
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