Why Does Hooke's Law Use a Negative Sign in Scalar Form?

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SUMMARY

This discussion centers on the application of Hooke's Law, specifically addressing the necessity of the negative sign in its scalar form. The equation is derived from Newton's second law, where the spring force is represented as ##\vec{F_s} = -k\vec{x}##, indicating that the force exerted by the spring opposes the displacement. The confusion arises when transitioning from vector notation to scalar notation, leading to misinterpretations of the signs associated with force and displacement. The consensus is that maintaining the negative sign is crucial for accurately representing the relationship between force and displacement in one-dimensional systems.

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  • Understanding of Newton's Second Law of Motion
  • Familiarity with vector notation and operations
  • Knowledge of Hooke's Law and its mathematical representation
  • Basic grasp of scalar versus vector quantities
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  • #31
kuruman said:
And then there is the recurrent question, "if I substitute numbers for g in the equation, do I use +9.8 m/s2 or -9.8 m/s2 ?"
Years ago I was using a textbook that forced the students to make that choice. In other words, ##g=\pm 9.8 \ \mathrm{m/s^2}##. That was a huge mistake.
 
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