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2.4 Exercise 35

Avg difficulty 2.5

Verify the normalization equation ∫0∞f(v)dv=1.\int_{0}^{\infty} f \left(v\right) d v = 1 . In doing the integral, first make the substitution u=m2kBTv=vvp.u = \sqrt{\frac{m}{2 k_{\text{B}} T}} v = \frac{v}{v_{p}} . This “scaling” transformation gives you all features of the answer except for the integral, which is a dimensionless numerical factor. You’ll need the formula

∫0∞x2e−x2dx=π4\int_{0}^{\infty} x^{2} e^{− x^{2}} d x = \frac{\sqrt{\pi}}{4}

to find the numerical factor and verify the normalization.

OpenStax University Physics Volume 2, 2.4 Distribution of Molecular Speeds, exercise 35

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Adapted from University Physics Volume 2 © 2016 Rice University. Licensed under CC BY 4.0. Source: University Physics Volume 2. Imported at revision db44eb9.