Trying to figure out the forces needed to push a heavy sliding door.

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Discussion Overview

The discussion revolves around the forces required to push a heavy sliding door, focusing on factors such as friction, inertia, and the dynamics of motion. Participants explore both theoretical and practical aspects of the problem, including the design of the door and its movement mechanics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant mentions the need to consider the force applied by the door on the wheels multiplied by the coefficient of friction, but expresses uncertainty about incorporating inertia into the calculations.
  • Another participant emphasizes the importance of overcoming the initial inertia to start moving the door, suggesting that the required force depends on the desired acceleration and speed.
  • A different viewpoint highlights that while inertia requires some energy, it is relatively small compared to the energy lost due to rolling friction and potential friction from ceiling guides.
  • One participant proposes using the formula FT = mv to approximate the force needed, referencing impulse as a related concept.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the exact factors or calculations needed to determine the force required to push the door. Multiple perspectives on inertia, friction, and the dynamics of motion are presented, indicating ongoing debate and exploration of the topic.

Contextual Notes

There are limitations regarding the assumptions made about the coefficients of friction, the effects of inertia, and the specific design features of the door, such as the presence of guides. The discussion does not resolve these complexities.

CuriousNotion
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I have been working with Physics for a while. I have recently come across a problem I could not solve efficiently. I have been designing a sliding door with 4 wheels with a rolling co efficient of 0.03. I thought that if I simply be using Force applied by door on all 4 wheels multiplied by friction I could find the force needed to push the door. However I just want to know if there are any other important factors I need to take into account (Im not sure how to incorporate Inertia)
 
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Well, if the door is initially still...you need to break this tendency of it to stay still...you need to apply a force to accelerate the door (F=ma) from v=0 to some reasonable speed v=v1 at which point (if you need to continue to open the door more) you can maintain such speed for a few more inches (at F=0.03*...) and THEN let go...

So, it all depends how quickly you want to open the door..you can accelerate at various rates...
 
Yes, there will be some energy required for inertia. But this is pretty small. Only 1/2mv^2, and v is going to be pretty small, so the energy required to overcome inertia is very small.

While the door is moving, the biggest energy loss is probably rolling friction. But the door will probably also require guides on the ceiling, so that the door doesn't move to the side. The friction between the door and these guides will also cause energy loss. By guides, I mean like grooves attached to the ceiling.

When you start to move the door from rest, you will notice it seems to take more force than when the door is already moving. This will be due to the wheels having sunk very slightly more into the floor, making it hard to move the door at first.
 
You can also approximate such a force via FT = mv assuming the force is a fixed value.
For more, see IMPULSE in wikipedia for example...

http://en.wikipedia.org/wiki/Impulse_(physics )
 
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