What is the Correct Equation for Calculating the Length of a Spring?

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Homework Help Overview

The discussion revolves around the correct equation for calculating the length of a spring, with references to energy equations and the relationship between mass, gravity, and spring constant.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the relationship between force and energy, questioning the validity of equating them. There are attempts to derive frequency equations for a mass on a spring and a simple pendulum, leading to a comparison of their respective formulas.

Discussion Status

Participants are exploring different interpretations of the equations involved and questioning the assumptions made in their derivations. Some guidance has been offered regarding the distinction between angular frequency and frequency, but no consensus has been reached on the correct approach to the problem.

Contextual Notes

There is mention of specific answer choices and a concern about the omission of certain factors in the final answer, indicating potential constraints in the problem setup or assumptions being made.

dinhjeffrey
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Homework Statement


http://img26.imageshack.us/i/1113001.jpg/

#12


Homework Equations



u=(1/2)kx^2
F=mg

The Attempt at a Solution



mg=(1/2)kx^2
√(2mg/k) = x

however, this is not any of the choices.
the correct answer is B)mg/k
 
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dinhjeffrey said:
mg=(1/2)kx^2
:confused: You seem to be setting a force equal to an energy. Not good.

What's the frequency of a mass on a spring? Of a simple pendulum? Compare.
 
okay i got the frequency of a mass of a spring is
f=√(g/L)/2π
and of a simple pendulum
w=√(k/m)

if i set them equal to each other i get
L = mg/(2πk) which is almost right, but the 2π is disregarded in the answer. does anyone know why?
 
ω is the angular frequency, not the frequency. To get f from ω, divide by 2pi.
 

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