Classically determining velocity of particle in a box

In summary, the conversation discusses using classical arguments to show that the speed of a particle in an infinite 1-D potential well can be calculated using the formula v= (nh)/(2mL). The concept of linear momentum and deBroglie's result for particle wavelength are mentioned, as well as the idea of constructive interference in a "box" with hard walls.
  • #1
whatupbaby
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Homework Statement


I am supposed to show, using a classical argument, that the speed "v" of a particle in an infinite 1-D potential well is

v= (nh)/(2mL)


Homework Equations





The Attempt at a Solution


Doesn't the particle just reflect back and forth against the walls of the well with a constant speed that it was given initially? How can I classically argue that Planck's constant is supposed to be in the velocity?
 
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  • #2
OK, it's "semi-classical": you use the classical concept of linear momentum ( p = mv ) , together with deBroglie's result for "particle wavelength" [itex] \lambda = \frac{h}{p} .[/itex]

Since the potential well is "infinitely high", it has "hard walls", which we've placed at a separation L . What sort of wave will constructive interference permit in such a "box"? What are the possible wavelengths?
 
  • #3
oh, that makes perfect sense. thanks!
 

1. How do you determine the velocity of a particle in a box using classical mechanics?

The velocity of a particle in a box can be determined by using the classical mechanics equation v = d/t, where v is velocity, d is distance, and t is time. In this case, the distance is the length of the box and the time is the period of oscillation of the particle.

2. What is the significance of determining the velocity of a particle in a box?

Determining the velocity of a particle in a box is important in understanding the behavior and properties of quantum systems. It can also provide insight into the energy levels and wave function of the particle.

3. Can the velocity of a particle in a box be determined using other methods besides classical mechanics?

Yes, the velocity of a particle in a box can also be determined using quantum mechanics, which takes into account the probabilistic nature of particles at the subatomic level. This method provides a more accurate and comprehensive understanding of the particle's velocity.

4. What are the assumptions made when using classical mechanics to determine the velocity of a particle in a box?

The assumptions made include treating the particle as a classical object with definite position and momentum, neglecting quantum effects such as wave-particle duality, and assuming the box walls to be perfectly rigid and impenetrable.

5. Are there any limitations to using classical mechanics to determine the velocity of a particle in a box?

Yes, classical mechanics is limited in its ability to accurately describe the behavior of particles at the subatomic level. It does not take into account quantum effects and can only provide an approximation of the particle's velocity in a box. Quantum mechanics is needed for a more precise understanding.

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