Classical Physics & Particle Motion Under Force Field

AI Thread Summary
The discussion centers on the application of Classical Physics versus Quantum Mechanics in analyzing the motion of a particle under a force field defined by the potential energy equation V(x)=1/2kx^2. Participants agree that Newton's Laws are appropriate due to the particle's small velocity, allowing for classical approximations. However, concerns about the implications of Quantum Mechanics and the Heisenberg Uncertainty Principle (HUP) arise, suggesting that specifying both position and velocity complicates the quantum analysis. Ultimately, the consensus leans towards using Newton's Laws for this scenario, as applying Quantum Mechanics would render the provided initial conditions meaningless. The conversation highlights the distinction between classical and quantum approaches in physics.
warhammer
Messages
164
Reaction score
33
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.
 
Physics news on Phys.org
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!
 
  • Like
Likes warhammer and Delta2
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!
 
  • Like
Likes Delta2
Thread 'Collision of a bullet on a rod-string system: query'
In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...
Back
Top