Simple harmonic motion - Springs

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Homework Help Overview

The discussion revolves around a problem related to simple harmonic motion, specifically involving a system of forces in a setup that may include springs or strings. The original poster expresses uncertainty about the forces acting on the masses and their respective equations of motion.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants discuss the identification of forces, the correct signs in the equations of motion, and the need for additional information regarding the system, such as the elastic constant and gravitational forces. There are questions about the natural length of the springs and the extent of compression or extension from the mean position.

Discussion Status

Some participants have pointed out potential ambiguities in the problem statement, while others have offered clarifications regarding the assumptions that can be made. The original poster indicates they have managed to solve the problem, suggesting some productive direction has been achieved.

Contextual Notes

There is a noted lack of specific information in the problem statement, including the elastic constant and details about the forces involved. The original poster's reference to both springs and strings has led to some confusion among participants.

Jalo
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Homework Statement



I have trouble determining the system of forces in systems with strings like the following:
2qxuxy9.jpg


Homework Equations





The Attempt at a Solution



My guess is it is:

x1=L/3 x2=2L/3

mass 1: -kx1+k(x2-x1)=m1a1
mass 2: -k(x2-x1)+kx1=m2a2

I'm not sure it is correct. Even if it is, anyone knows a good way to see the correct signs of the forces? I have some trouble identifying them...

Thanks ahead!
D.
 
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Hi Jalo! :smile:

I believe the question lacks information. Your title says springs and the question states strings. :-p

Alsos, there is nothing mentioned about the elastic constant 'k', nor about which forces do you require. If all the forces, it would have to include gravitational force too...
 
The criterion for SHM is that the restoring force be proportional to the displacement from the equilibrium postiion.
You have to the equilibrium configuration.
 
Last edited:
Infinitum said:
Hi Jalo! :smile:

I believe the question lacks information. Your title says springs and the question states strings. :-p

Alsos, there is nothing mentioned about the elastic constant 'k', nor about which forces do you require. If all the forces, it would have to include gravitational force too...

Constank k, no gravitational force, and just imagine it as springs. hope that helps :P
 
Jalo said:
Constank k, no gravitational force, and just imagine it as springs. hope that helps :P

What is their natural length? By how much are they compressed/extended from mean position??
 
Infinitum said:
What is their natural length? By how much are they compressed/extended from mean position??

The problem doesn't give any data other the one I wrote.
However I managed to solve the problem. Thanks to all who tried to help. :)

D.
 

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