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There is a spring with springs constant $k =200 N/m$. The spring is held vertically and a mass of 2 kg is attached to it. We will assume that $g=10 m/s^2$. The extension of the spring is to be found. The same can be found in two different ways.

  1. kx = mg --> x = 2*10/200 = 0.1 m
  2. The second method is using energy. The 2kg mass would lose GPE (loss of height = x), which would go into the spring as its strain potential energy. mgx = 0.5kx^2 --> x = 0.2m

Why are the two answers are different? I know that the first answer is correct, but why is the second method not correct? In fact, no matter what numbers I take, the second answer is always twice the first one.

Thanks in advance

golden_hawk21
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user15041899
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1 Answers1

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If you hang 2kg mass at a spring it moves beyond the equilibrium point and starts to oscillate around the 0,1m.

trula
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