Vertical spring and unattached mass

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Discussion Overview

The discussion revolves around the dynamics of a vertical spring and an unattached mass, specifically focusing on the conditions under which the mass separates from the spring after being pushed past its equilibrium point. The scope includes theoretical considerations of motion, forces, and equilibrium in an ideal spring system.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant inquires about the exact moment the object separates from the spring after being pushed past equilibrium.
  • Another participant asks what kind of motion results from pushing the object down past equilibrium and releasing it, under the assumption of an ideal spring and ignoring friction.
  • A different participant suggests that after the spring reaches its equilibrium, the elastic force acts only on the spring, implying that the object experiences infinite acceleration at the moment of separation, raising a question about the correctness of this assertion.
  • One participant states that an ideal spring ceases to exert force on the object the instant it reaches its relaxed length.
  • Further clarification is sought regarding whether the inquiry is about the force required to launch the mass or the timing of its separation from the spring.
  • Another participant requests information on the time or position at which the object is no longer in contact with the spring.
  • A later reply indicates that a previous participant has provided the answer to the question posed.

Areas of Agreement / Disagreement

Participants express differing views on the mechanics of the situation, particularly regarding the timing and conditions of separation. There is no consensus on the exact moment or conditions under which the object loses contact with the spring.

Contextual Notes

The discussion includes assumptions about ideal conditions, such as ignoring friction and the behavior of an ideal spring, which may not hold in practical scenarios. The implications of infinite acceleration and the definition of equilibrium are also points of contention.

Razvan
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Suppose I have a vertical spring and an object.
If I slowly put the object on the spring until it reaches the new equilibrium point, and then I push it more and after that I release it, when exactly will the object "separate" from the spring?
Thank you.
 
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If you push it down just a little past equilibrium and release it, what kind of motion results? Ignore friction and assume an ideal spring.
 
Last edited:
It doesn't matter how much more I push it past equilibrium, let's assume it is enough for the object to be "launched". For the part of the motion before reaching the original equilibrium point of the spring the motion is a known one, but I think that after the spring reaches its equilibrium, the elastic force acts on the spring alone (because the object is not tied to the spring). A force acting on an object with almost zero mass should result in an infinite acceleration, which means this should be the moment when the object is separated from the spring. Is this correct?
 
An ideal spring stops providing a force on the object the instant it reaches its relaxed length.
 
And that moment is the answer to my question, am I right? Thank you.
 
Razvan said:
It doesn't matter how much more I push it past equilibrium, let's assume it is enough for the object to be "launched".

The "when" that I assumed that you were asking about is "how hard do I have to push it down before the release will ultimately launch the mass so that it loses contact with the spring?"

Are you instead asking "how much time will elapse between when I release it and when it loses contact with the spring?"
 
How much time or the position where the object is no longer in contact with the spring.
 
Then CWaters has provided the answer.
 

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