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Homework Help: Newtons second law

  1. Oct 11, 2005 #1
    An advertisement claims that a particular automobile can "stop on a dime." What net force would actually be necessary to stop an automobile of mass (m) traveling initially at a speed of (v) in a distance equal to the diameter of a dime, which is (d) ?
     
  2. jcsd
  3. Oct 11, 2005 #2
    Σ F = -f = m*a

    I used the formula v2 = v_02 + 2a(x-x_0) to find the acceleration

    so a = (v2 – v_02) / 2(x-x_0) = ((0)2 – (v)2) / 2( d – 0)

    then my final answer would be ((0)2 – (v)2) / 2( d – 0) * mass
     
  4. Oct 11, 2005 #3
    but apparently this is incorrect. What am I doing wrong?
     
  5. Oct 11, 2005 #4

    Doc Al

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    Staff: Mentor

    Looks OK to me. (Simplify the final expression, of course.)
     
  6. Oct 11, 2005 #5

    Doc Al

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    Staff: Mentor

    What makes you think this is incorrect? Also: Just find the magnitude of the force.
     
  7. Oct 11, 2005 #6
    nevermind, it was correct. I incorrectly typed it in the program
     
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