Forces in Equilibrium - Tension in Strings

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Discussion Overview

The discussion revolves around a physics homework problem involving forces in equilibrium and tension in strings, specifically in a scenario with multiple masses and an incline. Participants explore how to analyze the system using free body diagrams and Newton's laws of motion.

Discussion Character

  • Homework-related
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant seeks guidance on calculating the tensions T1 and T2 when an additional mass is introduced into the system.
  • Another participant clarifies the directions of acceleration for the different blocks involved, emphasizing the need for free body diagrams to identify forces.
  • A participant expresses frustration with the problem and requests feedback on their workings if they attempt parts a and b of the question.
  • Feedback is provided on the diagrams, noting missing forces such as friction and the correct direction of weight, along with instructions on resolving weight components on the incline.

Areas of Agreement / Disagreement

Participants generally agree on the necessity of free body diagrams and the application of Newton's laws, but there is no consensus on the specific approach to solving the problem or the completeness of the diagrams presented.

Contextual Notes

Participants mention the need to account for various forces, such as friction and weight components, which may not be fully resolved in the provided diagrams. There is also uncertainty regarding the classification of the problem as a homework assignment or a take-home exam.

Who May Find This Useful

Students studying mechanics, particularly those dealing with forces in equilibrium and tension in multi-mass systems.

travi5
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Homework Statement



[PLAIN]http://img62.imageshack.us/img62/2120/derppz.jpg
Need to find T1 + T2I can do it when the two masses are connected to each other, I was just wondering how I'd do it now there is another 5kg in the middle?

Also if the acceleration is already given as 2m/s to the left, do I just plug that into F=ma for both Tensions?

Cheers
 
Last edited by a moderator:
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Actually, the acceleration of the center block is to the left, the acceleration of the hanging block is down, and the acceleration of the block on the incline is up parallel to the incline. The magnitude of each block's acceleration is the same. You must draw free body diagrams of each block to identify the forces acting on each block, and then use Newton's 2nd law on each block. Is this a homework problem or a take home exam?
 
PhanthomJay said:
Actually, the acceleration of the center block is to the left, the acceleration of the hanging block is down, and the acceleration of the block on the incline is up parallel to the incline. The magnitude of each block's acceleration is the same. You must draw free body diagrams of each block to identify the forces acting on each block, and then use Newton's 2nd law on each block. Is this a homework problem or a take home exam?

A past paper question
It's driving me crazy

If I attempt a and b, and post my workings would you be able to tell me where I'm going wrong?
 
Is this how the diagrams should look?

[PLAIN]http://img805.imageshack.us/img805/4020/diagrams.jpg
 
Last edited by a moderator:
The first diagram looks good. In the 2nd diagram, you are missing the friction force (uR) and its direction. In the third diagram, the weight always acts vertically down, not at an angle. This is the hardest of the diagrams...you have to break the weight up into its components parallel and perpendicular to the incline, then find the normal force and friction force ( as a function of the Normal force). Hint: the magnitude of the Normal force, R, in this diagram is equal to the component of the weight perpendicular to the incline.
 

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