How Do You Calculate Parameters for a Given Speed Distribution Function?

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Niko84
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Homework Statement



The speed distribution function of a group N particles is given by:
dNv=k*dv if U>v>0
dNv=0 if v>U

1) find k in terms of N and U.
2) draw a graph of distribution function
3) compute the average and rms speed in terms of U.
4) compute the most probable speed


Homework Equations



f(v)=[tex]\left[\frac{m}{2\pi\kappa*T}\right]^{\frac{3}{2}}*exp\left(-\frac{mv^{2}}{2\kappa*T}\right)[/tex] - Maxwell-Boltzmann distribution

[tex]\frac{dn_{v}}{n}[/tex]=4[tex]\pi*v^{2}*f(v)*dv[/tex] - speed distribution function

The Attempt at a Solution



1) k=4[tex]\pi*n*v^{2}*f(v)[/tex] - so I can draw a graph of the distribution function.
2) which function and how should I integrate in order to obtain k in terms of N and U?
3) is average speed = [tex]\int^{V}_{0}v*4\pi*v^{2}*f(v)dv[/tex] ?

Please help with the solution or link to a similar problem solution.
 
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Why do you invlove Maxwell-Boltzmann Distribution? Your given speed distrubtion was
dNv=k*dv if U>v>0
dNv=0 if v>U

Thus, you have for U>v>0: dN / N = k dv and for v >U: dN / N = 0

For a Maxwell-Boltzmann speed distribution you have ## \dfrac{dN}{N } = f(v) dv = 4\pi v^2\left( \dfrac{m}{2 \pi kT} \right)^{3/2} e^{-mv^2 / 2kT} \, dv##

You want to make sure your speed distribution is normalized, e.g. ## \int_0^\infty f(v) dv = N##
Which will turn to ## \int_0^U k dv = N## for your distribution.