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How do you find answer in Newton?(read)

  1. Nov 17, 2009 #1
    1. The problem statement, all variables and given/known data
    A person of weight 480 N stands on a scale in an elevator. What will the scale be reading in N when the elevator is accelerating downward at 6.7 m/s2 ?


    2. Relevant equations
    N= kg(m/s^2)


    3. The attempt at a solution
    Tried 480/9.81 = 48.929 times 6.7 equal 328 N
    Is this the right equation? If not, please tell me what equation or how to solve problem like this. Thank you.
     
  2. jcsd
  3. Nov 17, 2009 #2
    i'm afraid that's not right, if you think about it in net force;

    The net force is given by ma, which you worked out to be 328N;

    however this isn't what you're looking for, you're looking for the reaction from the floor of the lift on the person, you know that the net force is equal to the persons weight (downwards) minus the reaction force (upwards)

    [tex] ma (net force) = mg (weight) - reactionforce (reading on scale) [/tex]
     
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