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What is the largest mass that can be placed on the spring

  1. Apr 28, 2009 #1
    1. The problem statement, all variables and given/known data
    the spring in a typical hooke's law apparatus has a force constant of 1.50 N/m and a maximum extension of 10cm. what is the largest mass that can be placed on the spring without damaging it?


    2. Relevant equations
    what i believe to be relevant:
    F=-kx
    W=F"d
    E=mg(h)


    3. The attempt at a solution
    F=1.5(0.10)
    F=0.15

    W=F"d
    W=0.15(0.10)
    W=0.015J

    0.015=m(9.81)(0.10)
    0.015/0.981=m
    m=0.0153kg <----------- answer

    now i have no idea how this can be wrong.. i have gone over it many times now.
    my textbook has it as 0.153kg.
    am i right on this one?
     
  2. jcsd
  3. Apr 28, 2009 #2
    Re: springs

    I was able to solve this by using a force analysis. You don't need to even use energy.

    Try finding what mass puts the system in static equilibrium at the spring's maximum extension and solve for mass.

    There might be a way to solve it with the energy equations, but I don't really see a need to go that route. The only thing I can see is if you go that direction, the force exerted by the spring isn't constant, it's a function of x. But like I said, you don't even need to go that route.

    Draw a free body diagram and the answer should be obvious.
     
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