If the length of a 15cm spring increases to 42cm when a 4kg weight is hanging from it, what is the spring's constant?

1 Answer
Jan 19, 2016

I found 145.2Nm

Explanation:

I tried using Hooke's Law to describe the elastic force Fel, and Newton's law to describe the equilibrium of forces:
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According to our choice of axis the displacemeht can be considered negative (below the chosen origin) y=h=0.27m; so we get:
k=mgy=49.8(0.27)=145.2Nm