How Does the Speed Distribution Function Determine Vmin and Vmax?

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Homework Help Overview

The discussion revolves around determining the minimum and maximum speeds of particles based on a given speed distribution function, f(V) = AV(B - V)/B^3, where V is the particle speed and A and B are constants. Participants explore the characteristics of this distribution in the context of statistical mechanics.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants question the relationship between maximum speed, average speed, and most probable speed, with some suggesting that maximum speed cannot equal average speed. There are inquiries about the minimum speed where the distribution is non-zero and the implications of parameters A and B on the distribution's behavior.

Discussion Status

The discussion is active, with participants raising questions about the assumptions made regarding the parameters and the nature of the distribution. Some guidance is offered regarding the relationship between the distribution's characteristics and its mathematical formulation, but no consensus has been reached on the specific values of Vmin and Vmax.

Contextual Notes

There is uncertainty regarding the values of constants A and B, which affects the determination of minimum and maximum speeds. Participants are encouraged to visualize the distribution function through sketches to aid understanding.

reactor
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Dear
I have problem with determine the minimum speed in this problem , I think the the maximum speed equal to the average speed and the most probable speed can be obtain by derive equation and equally to zero .Is my solution correct?

The speed distribution function for N particles in a fixed volume is given by f (V) = AV(B - V)/B^3,
where V (>0) is the particle speed, and A and B are positive constants. Determine:
(a) The minimum speed Vmin and maximum speed Vmax.
b) The most probable speed where the probability density function is the largest.
 
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I think the the maximum speed equal to the average speed
If that would be true, all particles would have to have the same speed.

I have problem with determine the minimum speed in this problem
What is the minimal V where f(V) is not zero?
If you don't see that, make a sketch of f(V).

and the most probable speed can be obtain by derive equation and equally to zero
Right.
 
mfb said:
If that would be true, all particles would have to have the same speed.

What is the minimal V where f(V) is not zero?
If you don't see that, make a sketch of f(V).

Right.

the minimum when B=v=0 and what about the maximum
 
the minimum when B=v=0
Why B=?
A and B are parameters, you cannot set their values.

and what about the maximum
Did you draw the sketch I proposed? Do you see the maximum?
 
reactor said:
Dear
I have problem with determine the minimum speed in this problem , I think the the maximum speed equal to the average speed and the most probable speed can be obtain by derive equation and equally to zero .Is my solution correct?

The speed distribution function for N particles in a fixed volume is given by f (V) = AV(B - V)/B^3,
where V (>0) is the particle speed, and A and B are positive constants. Determine:
(a) The minimum speed Vmin and maximum speed Vmax.
b) The most probable speed where the probability density function is the largest.
First of all, this is not a Maxwellian distribution. The distribution is determined by this equation.

The minimum speed is the speed for which the distribution f(V) < 1. Since we don't know the values of A and B you cannot really determine that so assume it is very close to f(V) = 0.

How is the maximum related to the rate of change of f(V) with respect to V?

AM
 

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