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Pulling on a bar-what forces are in action?

  1. Nov 8, 2012 #1
    I aw wondering, if I pull on a bar but do not accelerate, according to newton's second law, the net forces equal zero,but what forces exactly are keeping me from accelerating? I know that there's the force of the bar on my hand, but I asked my teacher and she said that the other force is NOT the force of my hand on the bar. Any ideas?
  2. jcsd
  3. Nov 8, 2012 #2
    That question is not very clearly stated, so I'm not even sure what the question is. But I'll guess. The short answer is inertia. The bar exerts interia on your trying to accelerate it, so if you dont accelerate it, either its firmly fixed or you're firmly weak.

    As far as the counterforce NOT being your hand on the bar, that makes no sense. You defined the system that way. I'd ask the "teach" for greater clarification. Good luck!
  4. Nov 9, 2012 #3


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    Science Advisor

    I guess you stand on the floor and pull the bar horizontally? The other force acts on your feet horizontally (static friction).

    There are 3 forces acting on you, which as vectors add to zero:
    - Right from the bar
    - Down from gravity
    - Up & Left from the ground (Normal force & static friction component)
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