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Homework Help: Magnitude of normal force

  1. Jan 26, 2008 #1
    1. The problem statement, all variables and given/known data

    A small charge of -2 micro-colombs which has a mass of 0.5 kg lies on level ground. A charge of +5 micro-colombs is a distance of 0.35 meters above the charge. What is the magnitude of the normal force in Newtons on the -2 micro-colomb charge? Do not ignore gravity for this problem.

    2. Relevant equations

    F_e_=k[(q1q2)/r^2] F_m_=mg

    3. The attempt at a solution

    F_e_=0.7339 N and F_m_=4.9N

    Can anyone tell me if I'm going in the right direction with this problem?
  2. jcsd
  3. Jan 27, 2008 #2

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    If the upper charge had not been there, then normal reaction at point of contact on the ground would have been the weight mg. Now the upper charge is pulling at it with force F_e. How is the N changed now?
  4. Jan 27, 2008 #3
    The N is in the positive direction, going upward?
  5. Jan 28, 2008 #4

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    The normal reaction acting on the body at the point of contact is upward.
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