Why mass of spring/string assumed negligible?

  • Context: Undergrad 
  • Thread starter Thread starter cyt91
  • Start date Start date
  • Tags Tags
    Mass
Click For Summary

Discussion Overview

The discussion revolves around the assumption of negligible mass for springs, strings, or ropes in tension calculations. Participants explore the implications of this assumption on the uniformity of tension and the complexity of related calculations.

Discussion Character

  • Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant questions why the mass of springs/strings/ropes is often considered insignificant, seeking clarity on its effect on tension.
  • Another participant states that if the spring/string/rope is massless, the tension remains uniform throughout, suggesting that including mass complicates the problem.
  • It is noted that if the string has mass, it would also experience acceleration, necessitating the application of F=Ma for the string itself.
  • A participant inquires about the extent of complications that arise when considering mass in these calculations.
  • One response suggests that the inclusion of mass could lead to differential equations that are either significantly more complex or require numerical solutions, contrasting this with simpler solutions involving massless springs.

Areas of Agreement / Disagreement

Participants express differing views on the implications of including mass in tension calculations, with some arguing for the simplicity of massless models while others acknowledge the complexities introduced by mass.

Contextual Notes

The discussion does not resolve the assumptions regarding the mass of springs/strings/ropes or the specific conditions under which these assumptions hold. The limitations of the models and the mathematical complexities are acknowledged but not fully explored.

cyt91
Messages
51
Reaction score
0
In most questions I have encountered involving the calculation of tension in spring/string/rope, we are often asked to assume that the mass of the spring/string/rope to be insignificant. Why is this so? What effect does the mass of the spring/string/rope has on the tension of the spring/string/rope? I checked a few A-level books,none offered any satisfactory explanation.
 
Physics news on Phys.org
If the spring/string/rope is massless, then the tension is uniform throughout. (Otherwise, problems become too complicated.)
 
Also, if the string had mass then it would also have an acceleration when it is connected to a system. You would then be needed to write the F=Ma equation for the string also.
 
If you don't mind me asking, just how complicated things can be?
 
I think you'd get a differential equation that either:

1. is much more difficult to solve, or
2. can only be solved numerically (in current practice, with a computer)

With massless springs, it's just sines and cosines.
 

Similar threads

  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 19 ·
Replies
19
Views
16K
  • · Replies 11 ·
Replies
11
Views
3K
  • · Replies 14 ·
Replies
14
Views
3K
  • · Replies 131 ·
5
Replies
131
Views
9K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 5 ·
Replies
5
Views
3K
Replies
14
Views
3K
  • · Replies 10 ·
Replies
10
Views
6K
  • · Replies 2 ·
Replies
2
Views
2K