Calculating Work Needed to Stretch a Spring: 100J to 0.75m

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Discussion Overview

The discussion revolves around calculating the work needed to stretch a spring, specifically addressing the transition from a known work value for a certain distance to finding the work for an additional stretch. The scope includes mathematical reasoning and application of Hooke's law.

Discussion Character

  • Mathematical reasoning
  • Technical explanation
  • Homework-related

Main Points Raised

  • One participant calculates the work needed to stretch a spring and arrives at an incorrect conclusion, prompting a request for clarification on their mistake.
  • Several participants emphasize that work is not constant in a spring and that an integral should be used instead of the simple work formula W=Fd.
  • Another participant mentions forgetting Hooke's law, which relates force to displacement in springs, and suggests applying it to find the solution.
  • A participant proposes using the integral of kx to calculate work and suggests solving for the spring constant k using the known work value.

Areas of Agreement / Disagreement

Participants generally agree on the necessity of using an integral approach and the application of Hooke's law, but the specific calculations and interpretations of the problem remain unresolved.

Contextual Notes

There are limitations in the assumptions made regarding the spring constant and the integration limits, as well as potential confusion over the application of work formulas in the context of variable forces.

Who May Find This Useful

Students and individuals interested in physics, particularly those studying mechanics and the properties of springs, may find this discussion relevant.

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"It takes 100J of work to stretch a spring 0.5m from its equilibrium position. How much work is needed to stretch it an additional 0.75m."
Attempt: w = ⌠abF(x)dx
work = F x D
100J = F x 0.5m
F = 200J

0.75 + 0.5 = 1.25
w = ⌠0.51.25 200dx
w = 150 J

The correct answer: w = 525 J

what did I do wrong? Thanks!

Nevermind, I found the exact problem online, so sorry!
 
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Work is not constant in spring.You can't use W=Fd.You should take an integral
(Carefull for the signs when you take an integral).
Another thing that Questions ask "The work done by our force".
 
Arman777 said:
Work is not constant in spring.You can't use W=Fd.You should take an integral
(Carefull for the signs when u take an integral).
Another thing that Questions ask "The work done by our force".
My problem was that I forgot hooke's law.
F = kx
I can apply it to the given information to find the target solution.
 
Any ideas How ?
 
Arman777 said:
Any ideas How ?
w = ⌠.51.25 kx dx
you can solve for k by plugging in known integral...
100 = ⌠0.5kxdx

you should get k = 800
 
great
 

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