Find the mass of a thin funnel that is in the shape of a cone z = p x 2 + y 2 for 1 ≤ z ≤ 4, if the density at a point (x, y, z) is δ(x, y, z) = 10 − z.

Respuesta :

Answer:

[tex]mass=108\sqrt{2\pi }[/tex]

Step-by-step explanation:

First

[tex]\frac{dz}{dx}=\frac{x}{\sqrt{x^{2}+y^{2}  } }[/tex]

And

[tex]\frac{dz}{dy}=\frac{y}{\sqrt{x^{2} +y^{2} } }  \\m=\int\limits^{} \int\limits^{}_s {(10-z)} \, ds\\ m=\sqrt{2}\int\limits^{ } \int\limits^{}_{D} {(10-\sqrt{(x^{2}+y^{2}  } )} \, dA \\m=\sqrt{2}\int\limits^{2\pi }_{0}{ }  \int\limits^{4}_{1} {(10-r)} \, rdrdO\\ m=2\sqrt{2\pi } \int\limits^{4}_{1} {(10r-r^{2} )} \, dr\\ m=108\sqrt{2\pi }[/tex]