Pulley system problem: 6 Pulleys and 1 Mass

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Homework Help Overview

The discussion revolves around a pulley system problem involving a block of mass and the forces acting on it, specifically focusing on the tension in the strings and the application of free body diagrams.

Discussion Character

  • Conceptual clarification, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to analyze the system by labeling the strings and pulleys, creating free body diagrams, and establishing relationships between the tensions and forces. Some participants question the correctness of the reasoning and seek validation of the analysis presented.

Discussion Status

Participants are engaging in a supportive manner, with some offering positive feedback on the clarity of the original poster's reasoning. There is an ongoing exploration of the correctness of the analysis without reaching a definitive consensus.

Contextual Notes

The original poster expresses a lack of formal training in physics, which may influence their approach and understanding of the problem. There is an acknowledgment of the educational background and the resources used for self-study.

david3305
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Homework Statement
Find force F
Relevant Equations
m_1 = 5kg, g = 10 m/s^2
The following system is at rest with a block of mass m1 = 5kg, and a force F that is applied to the end of a string attached to the pulley system. Let g, the acceleration due to gravity equal to 10 (for simple calculations).

pulley1.jpg

My analysis is as follows:

I'll first label the strings Tsub1 and Tsub2, and each pulley in red P1 and P2 (in red):

pulley2.jpg


From here I'll make 3 free body diagrams:

m1:
pulley3.jpg

$$\begin{array}{rcl} & T_{1} = gm_{1} = 50N \\ \end{array}$$

then P1:
pulley5.jpg


$$\begin{array}{rcl} &T_{x} = 2T_{1} \end{array}$$

then P2:

pulley6.jpg


$$\begin{array}{rcl} &T_{x} = 2T_{2} \end{array}$$

From these equations we have that

$$\begin{array}{rcl} &T_{1} = T_{2} \end{array}$$

and therefore

$$\begin{array}{rcl} &T_{1} = T_{2} = F = 50N \end{array}$$
 
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Is there a question you wish to ask about this?
 
Sorry, I just wanted to know if my reasoning is correct. Im just a simple man trying to figure out stuff on my own without any formal training. In fact, I didn't even took physics in highschool, back in the day it wasn't required on my 3rd world country.
 
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david3305 said:
Sorry, I just wanted to know if my reasoning is correct. Im just a simple man trying to figure out stuff on my own without any formal training. In fact, I didn't even took physics in highschool, back in the day it wasn't required on my 3rd world country.
If you do/don't have formal training, your free body diagrams look well done/reasoned to me.
 
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erobz said:
If you do/don't have formal training, your free body diagrams look well done/reasoned to me.
Thanks, thats Khan Academy and a bunch of youtube videos for you.
 
david3305 said:
Sorry, I just wanted to know if my reasoning is correct. Im just a simple man trying to figure out stuff on my own without any formal training. In fact, I didn't even took physics in highschool, back in the day it wasn't required on my 3rd world country.
Your reasoning is correct. I wish that more of my students explained theirs as clearly as you did.
 
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