Pulley System Question: Find Relationship Between Force and Tension

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Discussion Overview

The discussion revolves around understanding the relationship between the force applied to a movable pulley system and the tension in the cable. Participants are exploring the mechanics of pulleys, specifically how different forces interact within the system.

Discussion Character

  • Homework-related
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that the tension in the cable is double the force applied at the free end, proposing the equation 2F = T.
  • Another participant questions the relationship by asking for clarification on what F2 and T represent in the context of the problem.
  • A different participant states that if the tension is given as 50N, then F equals T, implying a direct relationship under certain conditions.
  • Another reply emphasizes that the relationship between F and T depends on the definitions of F and T, noting that in some cases, they do not equate.
  • It is mentioned that under the assumption of a light and frictionless rope, the tension remains constant throughout the rope.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between force and tension, with no consensus reached. Some propose specific equations while others challenge the assumptions behind those equations.

Contextual Notes

There are limitations regarding the assumptions made about the pulley system, such as the neglect of friction and the weight of the rope, which may affect the validity of the proposed relationships.

GBA13
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Homework Statement


Hi Guys,

I am looking at a simple movable pulley system like the one two in from the left. I am trying to work out the relationship between the force applied to the free end (called F2 in the picture) and the tension in the cable

Homework Equations

The Attempt at a Solution

450px-Four_pulleys.svg.png
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I think that you add the tension in each section of cable so then 2F = T, the tension in the cable is double the force F2 but I'm not sure. Is that correct?

Thanks!
 
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But the tension in the cable is given in the figure. F2 equals ____?
 
PhanthomJay said:
But the tension in the cable is given in the figure. F2 equals ____?

The tension is 50N so then F = T, as it is for all the options here. Does that mean that F always = T?
 
"Does that mean that F always = T?"
What do you mean? What is F? And what is T?
Depends what F is and what T is. Here FL certainly doesn't equal the tension in the rope.

When we assume the rope is light and frictionless (which of course it never is!), then the tension in the rope is the same at all points.
 

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