SOS: Solving the Spring Constant of an Elastic Cord

AI Thread Summary
To determine the spring constant "k" of an elastic cord, two scenarios are analyzed using Hooke's law, which states that the force exerted by a spring is proportional to its extension. In the first scenario, a 73 N weight stretches the cord to 56 cm, while a 160 N weight stretches it to 81 cm. By expressing the forces and extensions as F1 = kx1 and F2 = kx2, two equations can be formed. These equations can be combined to solve for the spring constant "k" by considering the unstretched length of the cord. Understanding these relationships is essential for solving the problem effectively.
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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