Confusion about springs and hooke's law

Click For Summary

Discussion Overview

The discussion revolves around the application of Hooke's Law in the context of stretching a spring and the work done in the process. Participants explore the mechanics of force application on springs, the conditions necessary for stretching or compressing a spring, and the implications of stationary and moving ends.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant expresses confusion about the statement in their book regarding the application of force to both ends of a spring and questions how Hooke's Law applies in this scenario.
  • Another participant clarifies that to stretch or compress a spring, one end must be held stationary while force is applied to the other end, emphasizing that the net force on the spring must be zero.
  • A participant questions how a stationary spring can exert a force on a wall, referencing the negative force in Hooke's Law.
  • It is suggested that the displacement in Hooke's Law is relative to both ends of the spring, indicating that displacing one end affects the other end's position.
  • Another participant explains that the variable x in Hooke's Law represents the amount the spring is stretched from its unstressed length, noting that the restoring force acts at both ends of the spring.

Areas of Agreement / Disagreement

Participants demonstrate a lack of consensus on the interpretation of force application and the implications of Hooke's Law, with multiple competing views on how forces interact within the spring system.

Contextual Notes

There are unresolved assumptions regarding the definitions of force application and displacement in the context of Hooke's Law, as well as the conditions under which work is done on the spring.

ehabmozart
Messages
212
Reaction score
0
There is a statement in my book i can't really understand. "To stretch a spring, we must do work. We apply equal and opposite forces to the ends of a spring and gradually increase the forces. We hold the left end stationary, so the force we apply at this end does no work.The force at the moving end does do work" ... How is it we apply force on both ends of a spring. Doesn't hook's law apply for the end we actually stretch. F=kx? Kindly Clarify.. Thanks!
 
Physics news on Phys.org
If you apply force to only one end of the spring, the entire spring will simply accelerate. F=ma still works. If you want to stretch or compress the spring, something or someone must hold the other end of the spring stationary. In other words, the net force on the spring needs to be zero.
 
But then if it is stationary, how does the spring produce a force on the wall = -Fx??
 
Because x is not just displacement of an end point. It's displacement relative to the other end of the spring. If you displace one end by x, it's the same as displacing the other end by -x in terms of Hooke's Law.
 
Think of the x in Hooke's law as the amount by which the spring is stretched (from its unstretched length). As K^2 explains, the restoring force is exerted at both ends of the spring.
 

Similar threads

Undergrad Spring balance analysis from a system point of view
  • · Replies 24 ·
Replies
24
Views
2K
High School Why Does Hooke's Law Use a Negative Sign in Scalar Form?
  • · Replies 30 ·
2
Replies
30
Views
4K
High School How will a spring stretch in the following cases?
  • · Replies 17 ·
Replies
17
Views
2K
Undergrad Is Hooke's law really not working, or is it me being dummy?
  • · Replies 13 ·
Replies
13
Views
2K
Undergrad Thoughts about coupled harmonic oscillator system
  • · Replies 1 ·
Replies
1
Views
1K
High School A Question about Hooke's Law....
  • · Replies 4 ·
Replies
4
Views
2K
High School Hooke's Law and Restoring/Applied Force
  • · Replies 6 ·
Replies
6
Views
3K
High School Springboard physics questions for diving coach at YMCA
  • · Replies 12 ·
Replies
12
Views
3K
Undergrad Springs and Hooke's Law -- Unequal forces applied to the two ends....
  • · Replies 13 ·
Replies
13
Views
3K
High School Why Does a Spring Return to Its Original Position After Being Stretched?
  • · Replies 9 ·
Replies
9
Views
3K