Evaluate triple integral_W dx dy dz/(x^2 + y^2 + z^2)^3/2, where W is the solid bounded by the two spheres x^2 + y^2 + z^2 = a^2 and x^2 + y^2 + z^2 = b^2, where 0 < b < a.



Answer :

The Triple Intergral of the given expression is [tex]4 \pi \times ln (\frac{a}{b})[/tex]

[tex]\int\limits \int\limits \int\limits_w \frac{dx dy dz}{(x^2 + y^2 + z^2)^{\frac{3}{2}}}[/tex]

[tex]\text{Where } x^2 + y^2 + z^2 = a^2 \text{ and } x^2 + y^2 + z^2 = b^2, 0 < b < a[/tex]

Changing to Spherical Coordinates

[tex]b \leq \rho \leq a, 0 \leq \theta \leq 2 \pi, 0 \leq \phi \leq \pi[/tex]

[tex]\therefore x^2 + y^2 + z^2 = \rho^2; dx dy dz = \rho^2 sin \phi .d\phi .d\theta. d\rho[/tex]

[tex]\implies \int\limits^a_b \int\limits^{2\pi}_{0} \int\limits^{\pi}_{0} \frac{1}{\rho^3} \rho^2 sin \phi .d\phi .d\theta. d\rho[/tex]

[tex]=\int\limits^a_b {\frac{1}{\rho}} \, d\rho \int\limits^0_{2\pi} d\theta \int\limits^{\pi}_0 \sin{\phi} \, d\phi[/tex]

[tex]= [ln \rho]^{a}_{b} [\theta]^{2\pi}_{0} [-\cos \phi]^{\pi}_{0}[/tex]

[tex]= [\ln a - \ln b] \times [2\pi] \times [- \cos \pi - (-\cos 0)][/tex]

[tex]= 2\pi \times 2 \times (\ln a - \ln b)[/tex]

[tex]= 4 \pi \, \ln{\frac{a}{b}}[/tex]

To learn more about Integration, visit: https://brainly.com/question/14502499

#SPJ4