Help Solving Physics Problem: 2 Wires, Block & Velocity

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Homework Help Overview

The discussion revolves around a physics problem involving two wires and a block, specifically focusing on the relationship between the downward velocity of the wires and the upward velocity of the block. The problem includes a geometric aspect, as indicated by the mention of angles and the use of the Pythagorean theorem.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants explore the relationship between the velocities of the wires and the block, with one participant suggesting a potential solution of 2ucos(a). Others question this assumption and propose using geometric reasoning and differentiation to analyze the problem further.

Discussion Status

The discussion is ongoing, with participants providing different perspectives on the proposed solution. There is a suggestion to use the Pythagorean theorem and differentiation, indicating a productive direction in exploring the problem. However, there is no explicit consensus on the correct solution yet.

Contextual Notes

Participants are working with a visual representation of the problem, which may not be fully described in the text. There are indications of confusion regarding the correct interpretation of the velocities involved, and some participants express uncertainty about the validity of their assumptions.

phymatter
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Homework Statement



[URL=http://img18.imageshack.us/i/questionf.png/][PLAIN]http://img18.imageshack.us/img18/4880/questionf.png[/URL]

Uploaded with ImageShack.us[/PLAIN]

Homework Equations




if the 2 wires on both sides move with downward velocity u , with what velocity does the block rise , the angle with vertical is a ;

The Attempt at a Solution



i cannot figure out the solution, i think it should be 2ucos(a)
please help!1
 
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attachment.php?attachmentid=33299&stc=1&d=1300634118.png


consider the triangle in red

use Pythagoras theorem on it and differentiate it.

dh/dt is what you need and dl/dt is speed of string
what you think of db/dt ?
 

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thanks cupid.callin !
 
so is 2ucos(a) right? i think it should be!
 
Kartikc said:
so is 2ucos(a) right? i think it should be!

no its not ...

even i thought it should be but its not

try the way i told and you'll get the answer
 

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