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Homework Help: Finding the Mass of An Object as It Slides Over a Frictionless Surface

  1. Jan 18, 2012 #1
    1. The problem statement, all variables and given/known data

    The forearm (including the hand) has a mass of 4.26 kg. The upper arm exerts the force of 14 N on the forearm. If the forearm has an acceleration of 2.54 m/s^2, determine the mass of the object being pulled by the hand. (Assume the object slides over a frictionless surface.)

    2. Relevant equations

    Newton's Second Law:


    3. The attempt at a solution

    So I have my free bodies. With the arm, I have the three forces of Normal, Tension, and Mass, and with the object, the same three forces. I don't know if these are right so that might be why I'm stuck.

    Assuming that those free bodies are right, I am unsure of what equations (Newton's Second Law) to write down and use or what approach to take towards this problem.

    Any Help Would Be Great
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Jan 18, 2012 #2


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    Homework Helper

    Maybe I am oversimplifying . . . it looks like you have a force of 14 N causing an acceleration of 2.54 and you want to know what the mass is. Just use F = ma. Find m, then subtract 4.26 kg to get the mass of the object (excluding the forearm).
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