Solving Dynamics Question: F_spring & F_spring Potential

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SUMMARY

The discussion centers on solving a dynamics problem involving spring force and potential energy. The key equations are F_spring = ks and F_spring potential = 1/2ks^2. A participant incorrectly attempts to calculate the spring's stretch using the force directly in the potential energy equation, leading to an erroneous result of s = 0.632m. The correct approach involves recognizing that a spring force of 100 N corresponds to a stretch of 0.2 meters, indicating a normal length of 0.3 meters for the spring.

PREREQUISITES
  • Understanding of Hooke's Law (F_spring = ks)
  • Knowledge of potential energy in springs (F_spring potential = 1/2ks^2)
  • Basic trigonometry, specifically 3-4-5 triangles
  • Familiarity with Newton's laws of motion
NEXT STEPS
  • Study the application of Hooke's Law in various spring systems
  • Learn about energy conservation in mechanical systems
  • Explore the relationship between force, displacement, and potential energy in springs
  • Review problems involving trigonometric applications in physics
USEFUL FOR

Students studying physics, particularly those focusing on dynamics and mechanics, as well as educators seeking to clarify concepts related to spring forces and potential energy.

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Homework Statement


Screen Shot 2017-06-18 at 1.34.48 PM.png


Homework Equations



F_spring = ks and F_spring potential = 1/2ks^2

The Attempt at a Solution



So I recognize that @ theta = 0 it is a 3/4/5 triangle. The length of the spring is at .5m...furthermore the given spring force at that angle is 100 N. So why is it wrong to do 100 = (1/2) (500) (s)^2 ==>> s = .632m... Why should I use F= ks

Everything else I understand...
 
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Maybe I don't understand what you're trying to do, but it looks like you're plugging in the force of the spring where the potential energy should go.

If you know that the spring applies 500 Newtons for every meter its stretched, if it's applying 100 Newtons, it must have been stretched 0.2 meters (and therefore its normal length is 0.3 meters). That would allow you to find the potential energy in the spring. (Again, if I'm misunderstanding the problem, please tell me).
 

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