How can tension be the same along all points in a rope?

  • Context: Undergrad 
  • Thread starter Thread starter FisherDude
  • Start date Start date
  • Tags Tags
    Points Rope Tension
Click For Summary

Discussion Overview

The discussion revolves around the concept of tension in a rope when a weight, such as a bird, lands on it. Participants explore how the tension varies depending on the position of the weight along the rope, particularly in the context of a sagging wire between two poles. The scope includes theoretical reasoning and conceptual clarification regarding the mechanics of tension in ropes.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant presents a scenario where a bird lands on a wire and questions how tension can remain the same along the wire if the bird is not positioned midway.
  • Another participant introduces an extreme case of a weight hanging vertically from a wire, suggesting that the tension is not uniform along the wire in this situation.
  • Some participants agree that if the bird lands closer to one pole, the tension on each side of the wire would differ due to varying angles.
  • It is noted that the horizontal components of the tensions must cancel, indicating that the tension magnitudes will differ if the angles are different.
  • One participant concludes that the tension in the rope closest to a pole carries more vertical weight, resulting in higher tension compared to the other side.

Areas of Agreement / Disagreement

Participants express differing views on whether tension can be the same along all points in the rope, with some agreeing that it varies based on the position of the weight and the angles involved. The discussion remains unresolved regarding the uniformity of tension in different scenarios.

Contextual Notes

The discussion highlights the dependence on the position of the weight and the angles formed by the wire, which are not fully resolved. Assumptions about the uniformity of tension are challenged without reaching a consensus.

FisherDude
Messages
23
Reaction score
0
Consider the following problem: The distance between two telephone poles is 50.0 m. When a 1.00-kg bird lands on the telephone wire midway between the poles, the wire sags 0.200 m. How much tension does the bird produce in the wire? Ignore the weight of the wire.


The tension is 613 N. But what if the bird didn't land midway, but instead, for example, somewhere closer to one of the poles? Wouldnt the tension in each side of the wire (relative to the bird) be a different number than the tension in the other side? (since it seems that the angle between one side of the wire and the horizontal would differ for both sides in this case) So how can the tension be the same? Unless the tension in each side would be the same no matter where the bird landed..

Thanks in advance.
 
Physics news on Phys.org
Take an extreme case. A weight hangs vertically from a wire mounted to a pole, and the wire also continues on to be connected to another pole. Here it's clear that the tension between the two parts of the wire is not the same.
 
rcgldr said:
Take an extreme case. A weight hangs vertically from a wire mounted to a pole, and the wire also continues on to be connected to another pole. Here it's clear that the tension between the two parts of the wire is not the same.

agreed.
So
The tension is 613 N. But what if the bird didn't land midway, but instead, for example, somewhere closer to one of the poles? Wouldnt the tension in each side of the wire (relative to the bird) be a different number than the tension in the other side?
yes I think that's right.
 
Since the horizontal components of the tensions must cancel, the magnitude will be different ilf the angles are different. You are right.
 
pam said:
Since the horizontal components of the tensions must cancel, the magnitude will be different ilf the angles are different. You are right.

That's it exactly.
.'. The tension in the rope closest to a pole carries most of the vertical weight, and so has a higher tension.
 

Similar threads

Undergrad People pulling rope, one in a perpendicular direction
  • · Replies 16 ·
Replies
16
Views
3K
Solve The Laws of Motion: Tension in a Bird on a Wire
  • · Replies 2 ·
Replies
2
Views
2K
Undergrad How can I solve catenary problems?
  • · Replies 1 ·
Replies
1
Views
2K
Rope Swing, starting in tension vs slack
  • · Replies 3 ·
Replies
3
Views
2K
High School How can I calculate the tension in a rope?
  • · Replies 12 ·
Replies
12
Views
16K
Calculating Tension in a Telephone Wire with Mass and Angle
  • · Replies 5 ·
Replies
5
Views
3K
How to calculate Tension for a series of connected points?
  • · Replies 8 ·
Replies
8
Views
3K
Calculating Tension in a Wire with a Perched Bird: A Physics Problem
  • · Replies 9 ·
Replies
9
Views
8K
Tension at all various of a wire rope subjected to tension
  • · Replies 1 ·
Replies
1
Views
2K
Why Does Tension Vary Along the Rope in a Hanging Superhero Scenario?
  • · Replies 5 ·
Replies
5
Views
8K