A bead is made by drilling a cylindrical hole of radius 1 mm through a sphere of radius 5 mm. Set up a triple integral in cylindrical coordinates representing the volume of the bead. Evaluate the integral.

Respuesta :

Answer: Volume = 64π[tex]\sqrt{6}[/tex] mm³

Step-by-step explanation: A triple integral is generally used to calculate the volume of a region. In this case, the integral will be

V = [tex]\int\limits^a_b {\int\limits^a_b {\int\limits^a_b \, dV[/tex]. The limits of the triple integral will be:

1≤r≤5, in which r is the radius of the sphere;

0≤θ≤2π, which θ is the angle of the sphere;

and the limits determined by the bead;

To find the limits of the bead, we use the cylinfrical coordinates. In it, the sphere is represented by the equation [tex]r^{2} + z^{2} = 25[/tex]

So, the region of the bead will be:

[tex]r^{2} + z^{2} = 25[/tex]

z = ±[tex]\sqrt{25 - r^{2} }[/tex]

- [tex]\sqrt{25 - r^{2} }[/tex] ≤ z ≤ [tex]\sqrt{25 - r^{2} }[/tex]

Calculating and substituing:

volume = [tex]\int\limits^A_B \, dV[/tex]

volume = ∫∫∫ r dzdθdr

volume = ∫∫ rz dθdr

Using the limits for z:

volume = ∫∫ r·(√25 - r²) + r·(√25 - r²) dθdr

volume = ∫∫ 2r[tex]\sqrt{25-r^{2} }[/tex]dθdr

volume = ∫ 2r[tex]\sqrt{25-r^{2} }[/tex]∫dθdr

Using the limits for r and θ, we have:

volume = 2π · [[tex]\frac{-2}{3}[/tex][tex](25 - 5^{2} )^{\frac{3}{2} }[/tex] + [tex]\frac{2}{3} (25 - 5^{2} )^{\frac{3}{2} }[/tex] ]

volume = 64π[tex]\sqrt{6}[/tex] mm³

The volume of a bead inside a sphere is 64π[tex]\sqrt{6}[/tex] mm³