Newtonian Mechanics/Forces Question

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Homework Help Overview

The discussion revolves around a problem in Newtonian mechanics involving the tension in cords suspending buckets, each with a mass of 3.5 kg. Participants explore the effects of upward acceleration on the tensions in the cords and the implications of force diagrams.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the application of Newton's second law to each bucket and the relationship between applied forces and tension in the cords. Questions arise regarding the nature of the forces acting on the system, particularly when the apparatus accelerates upwards.

Discussion Status

Some participants express confusion about the relationship between applied forces and tension, while others provide insights into the mechanics of the system. There is a recognition of the role of tension in mediating the forces acting on the buckets, and some clarity appears to be emerging regarding the dynamics involved.

Contextual Notes

Participants are navigating the complexities of force diagrams and the distinction between equilibrium and accelerating systems. There is an acknowledgment of the need for proper formatting in questions, indicating a structured approach to the discussion.

MyNameIsNicholas
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These buckets are being suspended. The cords have no mass and each bucket is 3.5 kg.

a.) Find the tension in the upper cord (T1) and the lower cord (T2)
b.) If the apparatus is pulled upwards from the top of the upper cord, what are the new tensions of each cord?

I understand the first part. The force diagrams consist of:
(Upper Bucket): T1 upwards, T2 downwards, and Fg downwards
(Lower Bucket): T2 upwards and Fg downwards

However, when the apparatus accelerates upwards, the tensions in both cords increases. This makes sense physically but in the force diagram isn't force applied (causing acceleration) going upwards? And if that were the case, then force applied would counter-intuitively decrease the tension within the cords. Can someone graciously clear this up for me?
 
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Newton's second law applies to each bucket independently.
 
MyNameIsNicholas said:
4_41.gif


These buckets are being suspended. The cords have no mass and each bucket is 3.5 kg.

a.) Find the tension in the upper cord (T1) and the lower cord (T2)
b.) If the apparatus is pulled upwards from the top of the upper cord, what are the new tensions of each cord?

I understand the first part. The force diagrams consist of:
(Upper Bucket): T1 upwards, T2 downwards, and Fg downwards
(Lower Bucket): T2 upwards and Fg downwards

However, when the apparatus accelerates upwards, the tensions in both cords increases. This makes sense physically but in the force diagram isn't force applied (causing acceleration) going upwards? And if that were the case, then force applied would counter-intuitively decrease the tension within the cords. Can someone graciously clear this up for me?
I'm not sure why you would believe that's the case, but look at ##\sum F = ma##. Solve for the tension, and you'll see why hopefully. You may be confusing systems in equilibrium and accelerating systems while doing the FD.

Edit, trying to think of a good way to explain what I think is catching you up, but anyway, what's actually accelerating the system upward? The reactionary tension of course! The force that's pulling the system upward itself isn't applied to the buckets, its mediated by the tension in the rope.

Not sure if that helps or not.
 
Last edited:
I think I understand! The FA isn't actually an applied force. Well it is, but in terms of this problem it isn't. It's actually just addition upward tensional force on the upper cord FT1! This would, obviously, increase FT1 and in turn increase FT2. Thanks for the help and sorry for not using the proper format of my question. Merci.
 

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MyNameIsNicholas said:
I think I understand! The FA isn't actually an applied force. Well it is, but in terms of this problem it isn't. It's actually just addition upward tensional force on the upper cord FT1! This would, obviously, increase FT1 and in turn increase FT2. Thanks for the help and sorry for not using the proper format of my question. Merci.

Edit: Ignore those files. I was going to ask a follow-up question but upon creating those images and thinking about the question, it clicked!
 

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