---
title: "An elastic cord is \\( 80. \\) \\( \\text{cm} \\) long when it is supporting a mass of \\( 10. \\) \\( \\text{kg} \\) hanging from it at rest. When an additional \\( 4.0 \\) \\( \\text{kg} \\) is added, the cord is \\( 82.5 \\) \\( \\text{cm} \\) long. "
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url: "https://nerd-notes.com/ubq/100898/"
date_modified: "2025-09-15T02:42:55+00:00"
---

# An elastic cord is \( 80. \) \( \text{cm} \) long when it is supporting a mass of \( 10. \) \( \text{kg} \) hanging from it at rest. When an additional \( 4.0 \) \( \text{kg} \) is added, the cord is \( 82.5 \) \( \text{cm} \) long. 

An elastic cord is \( 80\) \( \text{cm} \) long when it is supporting a mass of \( 10. \) \( \text{kg} \) hanging from it at rest. When an additional \( 4.0 \) \( \text{kg} \) is added, the cord is \( 82.5 \) \( \text{cm} \) long.

**Part a)** What is the spring constant? *(3 points)*

**Part b)** What is the original length of the cord (with no mass)? *(3 points)*


*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/100898/*