FBDs for Box and Magnet Lifting by a Rope Attached to Ceiling

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Homework Help Overview

The problem involves analyzing a scenario where a box is lifted by a magnet suspended from the ceiling via a rope. Participants are tasked with drawing free body diagrams (FBDs) for both the box and the magnet, while questioning the presence of normal forces in the context of the setup described.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss whether a normal force should be included in the FBD, particularly considering that the box is not in direct contact with the ceiling. There is exploration of the definitions and implications of reaction forces in this context.

Discussion Status

The discussion is ongoing, with participants providing insights about the nature of forces involved. Some guidance has been offered regarding the inclusion of forces in the FBD, particularly around the concept of normal forces and their relevance when objects are not in contact.

Contextual Notes

Participants are navigating the definitions of forces and their applicability in the context of the problem, particularly focusing on the relationship between the box, the magnet, and the ceiling.

cmkc109
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Homework Statement



A box is lifted by a magnet suspended from the ceiling by a rope
attached to the magnet as illustrated in Fig 3.65. Draw free body
diagram for the box and for the magnet

so the picture is basically there is a ceiling , and the rope hanging from the ceiling to the magnet, and the magnet is attached to the box (located below the magnet)

I am wondering, will there be a normal force in the FBD since the ceiling is the surface? but wouldn't the Fn and Fg be in the same direction? or will it be no Fn because the object and the surface are not in direct contact?

Homework Equations





The Attempt at a Solution

 
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For every force there is an equal in magnitude and opposite in direction reaction force. "Normal force" is a name usually given to a particular kind of reaction force. Using that name in other contexts might be confusing. So, yes, there are reaction forces, but you probably shouldn't call them "normal forces".
 
tms said:
For every force there is an equal in magnitude and opposite in direction reaction force. "Normal force" is a name usually given to a particular kind of reaction force. Using that name in other contexts might be confusing. So, yes, there are reaction forces, but you probably shouldn't call them "normal forces".


so do u include it in the FBD?
 
what i am trying to ask it, should this force be included when the object is not in directly contact with the surface
 
You use all forces in the diagram.
 
cmkc109 said:
what i am trying to ask it, should this force be included when the object is not in directly contact with the surface
If the object is not in contact with the surface, there can be no normal force between them. Since it doesn't exist, you wouldn't include it.
 
ψ
Doc Al said:
If the object is not in contact with the surface, there can be no normal force between them. Since it doesn't exist, you wouldn't include it.

thanks for ur reply!
 

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