Solve Free Body Diagram: 2 Boxes, m1=35kg, m2=45kg

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Homework Help Overview

The problem involves two boxes with masses m1=35kg and m2=45kg, connected by a rope over a horizontal rod. The system is set in motion from rest, and participants are tasked with determining the acceleration, tension in the rope, and displacement after a certain time. The context is centered around free body diagrams and the application of Newton's laws.

Discussion Character

  • Exploratory, Conceptual clarification, Problem interpretation

Approaches and Questions Raised

  • Participants express uncertainty about the problem's wording and the correct interpretation of the setup. There are discussions about how to draw the free body diagram and the forces acting on each box. Some suggest treating the rod as a frictionless pulley and applying Newton's second law to each mass.

Discussion Status

The discussion is ongoing, with participants sharing their interpretations and clarifying the setup. Some guidance has been provided regarding the application of Newton's laws and the importance of a consistent sign convention. However, there is no explicit consensus on the interpretation of the problem or the approach to take.

Contextual Notes

Participants are grappling with the clarity of the problem statement and the assumptions regarding the system's setup, particularly concerning the friction and mass of the rod. There is an indication that the original poster may have misinterpreted the arrangement of the boxes and the rope.

cindy!
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Homework Statement



Two boxes of masses m=35kg and m2=45kg, are hung vertically from opposite ends of a rope passing over a rigid horizontal metal rod. They system starts moving from rest. Assuming that friction between the rod and the rope is negligible, determine the magnitude of
(a) the acceleration of the boxes
(b) the tension in the rope
(c) the magnitude of each box's displacement after 0.5s

Homework Equations



Fnet=ma
Fnet= FT - Fg
ma=FT-Fg

(well i think this is right, depending on how the free body diagram is drawn..)


The Attempt at a Solution



Well...I have no idea what the question is saying, I am unsure how to draw the actual diagram and also how to draw the FBD. This is how i inteperted it:

2dtzqs5.jpg


4bso6zq.jpg
 
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maybe I am reading it wrong, but the way i read it was that there are 2 boxes tied to each other with a rope and that rope is hung on an iron bar.
 
What's F_R in your diagram?? I agree with fizz on the interpretation of the problem.
 
I assume you are to treat this just as you would if the rod were a frictionless (and massless) pulley. Draw a free body diagram for each mass separately.

Apply Newton's 2nd law to each mass (just like in your equations) to get two equations, which you'll solve together. Hint: Adopt a consistent sign convention, for example: up is positive and down is negative. Let "a" be the magnitude of the acceleration; how do the accelerations of the masses relate to each other?
 

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