What kind of Physics Laws would be applied to this problem about a potential field?

warhammer

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.

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PeroK

Homework Helper
Gold Member
2018 Award
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?

Delta2

Homework Helper
Gold Member
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?

warhammer

How much do you know about QM?
I have just started to understand the basics so I know very little.

PeroK

Homework Helper
Gold Member
2018 Award
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!

• warhammer and Delta2

warhammer

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!

• Delta2

"What kind of Physics Laws would be applied to this problem about a potential field?"

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