Classical Physics & Particle Motion Under Force Field

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Homework Help Overview

The discussion revolves around a particle moving under a force field described by the potential energy equation V(x)=1/2kx^2. The context involves determining the appropriate physical laws to apply given the particle's small velocity and initial conditions.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the applicability of Newton's Laws versus quantum mechanics, questioning the sufficiency of the provided data for each approach. Some express uncertainty about the transition between classical and quantum descriptions based on the particle's characteristics.

Discussion Status

The discussion is active with participants sharing their understanding of classical and quantum mechanics. Some guidance is offered regarding the implications of the Heisenberg Uncertainty Principle (HUP) on the problem, and there is an ongoing exploration of the criteria for choosing between classical and quantum approaches.

Contextual Notes

Participants note the initial conditions provided in the problem, including the particle's position and velocity, and discuss how these may influence the choice of physical laws. There is an acknowledgment of the limitations of the information given for a quantum mechanical analysis.

warhammer
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Homework Statement
A particle of mass m moves under a force field corresponding to the potential energy V(x)=1/2kx^2 . It is given that at a certain instant t=0 , it is at x = 0 and its velocity is small and given by v=v0(i) . To get the subsequent motion,
(a) Newton’s laws of motion can be used
(b) Laws of quantum mechanics can be used
(c) This much data is not sufficient
(d) Laws of relativity must be applied
Relevant Equations
Given Potential Energy V(x)=1/2kx^2.
The particle is moving under a force field with the potential energy equation described above. I find it logical that Newton's Laws can be used as in the question itself it is stated that the velocity is quite small and we could approximate its subsequent motion via the notions of Classical Physics. Is my approach correct, because I also feel that being a single particle QM would come into play and consequently HUP which would make option (c) the correct one.
 
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warhammer said:
Homework Statement: A particle of mass m moves under a force field corresponding to the potential energy V(x)=1/2kx^2 . It is given that at a certain instant t=0 , it is at x = 0 and its velocity is small and given by v=v0(i) . To get the subsequent motion,
(a) Newton’s laws of motion can be used
(b) Laws of quantum mechanics can be used
(c) This much data is not sufficient
(d) Laws of relativity must be applied
Homework Equations: Given Potential Energy V(x)=1/2kx^2.

The particle is moving under a force field with the potential energy equation described above. I find it logical that Newton's Laws can be used as in the question itself it is stated that the velocity is quite small and we could approximate its subsequent motion via the notions of Classical Physics. Is my approach correct, because I also feel that being a single particle QM would come into play and consequently HUP which would make option (c) the correct one.

How much do you know about QM?
 
Quantum mechanics usually are applied for particles of the microscopic world, while classical physics for the macroscopic world. So what do you think is the criterion here to decide between a) and b) and do we have enough info about this criterion?
 
PeroK said:
How much do you know about QM?
I have just started to understand the basics so I know very little.
 
warhammer said:
I have just started to understand the basics so I know very little.

In QM you'd be given an initial wavefunction for the particle.

The HUP implies that being given the initial position and velocity is problematic for a quantum particle!
 
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PeroK said:
In QM you'd be given an initial wavefunction for the particle.

The HUP implies that being given the initial position and velocity is problematic for a quantum particle!
Oh now I understand. If QM were to be applied here then the initial position and the velocity both specified in the question would render it meaningless. Thus, Newton's Laws can be used for the particle's motion. Thank you!
 
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