SOS: Solving the Spring Constant of an Elastic Cord

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Homework Help Overview

The problem involves determining the spring constant of an elastic cord based on its lengths under different weights. The context is rooted in the principles of elasticity and Hooke's law.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss applying Hooke's law to the problem, with some suggesting to express the forces and extensions for each weight scenario. Others express confusion about combining equations and seek clarification on the approach.

Discussion Status

The discussion is ongoing, with participants exploring different methods to set up the problem. Some guidance has been offered regarding the use of Hooke's law and simultaneous equations, but there is no consensus on the best approach yet.

Contextual Notes

Participants mention a lack of understanding and clarity in the problem setup, indicating that the original poster and others are struggling with the concepts involved.

Sean1082
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Homework Statement


An elastic cord is 56 cm long when a weight of 73 N hangs from it but is 81cm long when a weight of 160 N hangs from it.

What is the spring constant "k" of this elastic cord?

Homework Equations


mg=kx


The Attempt at a Solution



No idea... my teacher doesn't know how to teach physics and the whole class is completely lost.
 
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Express what Hooke's law says for each situation:
F1 = kx1
F2 = kx2

Combine those equations and see what you can deduce.
 
I have no idea what you mean by combine...
 
Another way to solve this is to call the unknown unstretched length of the spring L. Now write Hooke's law for each of the given conditions. You'll have two equations which you can solve simultaneously.
 

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