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

In summary, a box is lifted by a magnet suspended from the ceiling by a rope. The free body diagrams for the box and magnet would show all forces, including reaction forces, but it is not necessary to label them as "normal forces" in this context. If the object is not in contact with the surface, there will be no normal force between them and it should not be included in the diagram.
  • #1
cmkc109
103
0

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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  • #2
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".
 
  • #3
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?
 
  • #4
what i am trying to ask it, should this force be included when the object is not in directly contact with the surface
 
  • #5
You use all forces in the diagram.
 
  • #6
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.
 
  • #7
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!
 

1. How does the force of gravity affect the box and magnet in this scenario?

The force of gravity acts on both the box and the magnet, pulling them downwards towards the ground. This force is counteracted by the tension force in the rope attached to the ceiling, allowing the box and magnet to be lifted upwards.

2. What other forces are involved in this situation besides gravity and tension?

Friction may also play a role in this scenario, depending on the surface the box and magnet are resting on. If there is significant friction between the box and the surface, it may require more force to lift the box and magnet. Additionally, if the rope is not perfectly vertical, there may be a slight component of horizontal force acting on the box and magnet.

3. How does the weight of the box and magnet affect the amount of force needed to lift them?

The weight of the box and magnet will determine the amount of force needed to lift them. The heavier the objects, the more force will be required to overcome the force of gravity and lift them.

4. Is the force of tension in the rope constant throughout the lifting process?

No, the force of tension in the rope will vary throughout the lifting process. As the box and magnet are lifted, the tension force will increase to counteract the force of gravity. Once the objects are lifted and stationary, the tension force will remain constant until it is released.

5. How does the angle of the rope affect the amount of force needed to lift the box and magnet?

The angle of the rope will affect the amount of force needed to lift the box and magnet. As the angle of the rope becomes more horizontal, the tension force will need to increase to counteract the horizontal component of the force of gravity. This means that more force will be needed to lift the objects at a greater angle than if the rope were vertical.

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