1. **Problem Statement:**
We are given a solid region $Q$ bounded by:
- Outer sphere: $x^2 + y^2 + z^2 = 16$
- Inner sphere: $z^2 + y^2 = 4 - x^2$
- Planes: $y \geq x$, $z \geq 0$, and $z \leq 4$
We need to:
(i) Derive the integral for $\iiint_Q \frac{\sqrt[3]{(x^2 + y^2 + z^2)^2}}{2} \, dV$ using spherical coordinates.
(ii) Determine the volume of the solid $Q$.
---
2. **Understanding the boundaries:**
- Outer sphere radius $R=4$ since $x^2 + y^2 + z^2 = 16$.
- Inner sphere rewritten: $z^2 + y^2 = 4 - x^2$ implies $x^2 + y^2 + z^2 = 4$, so inner sphere radius $r=2$.
- Planes restrict the region further.
3. **Spherical coordinates:**
Use:
$$
\begin{cases}
x = \rho \sin\phi \cos\theta \\
y = \rho \sin\phi \sin\theta \\
z = \rho \cos\phi
\end{cases}
$$
where $\rho \geq 0$, $0 \leq \phi \leq \pi$, $0 \leq \theta < 2\pi$.
Volume element:
$$dV = \rho^2 \sin\phi \, d\rho \, d\phi \, d\theta$$
4. **Bounds for $\rho$:**
Between inner and outer spheres:
$$2 \leq \rho \leq 4$$
5. **Bounds for $\phi$ and $\theta$ from planes:**
- $z \geq 0 \Rightarrow \cos\phi \geq 0 \Rightarrow 0 \leq \phi \leq \frac{\pi}{2}$ (upper hemisphere)
- $z \leq 4$ is automatically satisfied since $\rho \leq 4$ and $\cos\phi \leq 1$.
- $y \geq x$ means $\sin\phi \sin\theta \geq \sin\phi \cos\theta$; since $\sin\phi \geq 0$ for $0 \leq \phi \leq \pi$, divide both sides by $\sin\phi$:
$$\sin\theta \geq \cos\theta \Rightarrow \tan\theta \geq 1$$
This implies:
$$\theta \in \left[\frac{\pi}{4}, \frac{5\pi}{4}\right]$$
6. **Integral for (i):**
The integrand:
$$\frac{\sqrt[3]{(x^2 + y^2 + z^2)^2}}{2} = \frac{\sqrt[3]{\rho^4}}{2} = \frac{\rho^{4/3}}{2}$$
Integral:
$$
\iiint_Q \frac{\rho^{4/3}}{2} \, dV = \int_{\theta=\pi/4}^{5\pi/4} \int_{\phi=0}^{\pi/2} \int_{\rho=2}^4 \frac{\rho^{4/3}}{2} \cdot \rho^2 \sin\phi \, d\rho \, d\phi \, d\theta
$$
Simplify integrand:
$$\frac{\rho^{4/3}}{2} \cdot \rho^2 = \frac{\rho^{4/3 + 2}}{2} = \frac{\rho^{10/3}}{2}$$
So:
$$
\int_{\pi/4}^{5\pi/4} \int_0^{\pi/2} \int_2^4 \frac{\rho^{10/3}}{2} \sin\phi \, d\rho \, d\phi \, d\theta
$$
7. **Integral for (ii) volume:**
Volume is:
$$
\iiint_Q dV = \int_{\pi/4}^{5\pi/4} \int_0^{\pi/2} \int_2^4 \rho^2 \sin\phi \, d\rho \, d\phi \, d\theta
$$
---
**Final answers:**
(i) Integral for given function:
$$
\boxed{\int_{\pi/4}^{5\pi/4} \int_0^{\pi/2} \int_2^4 \frac{\rho^{10/3}}{2} \sin\phi \, d\rho \, d\phi \, d\theta}
$$
(ii) Volume integral:
$$
\boxed{\int_{\pi/4}^{5\pi/4} \int_0^{\pi/2} \int_2^4 \rho^2 \sin\phi \, d\rho \, d\phi \, d\theta}
$$
Spherical Integrals Ab0573
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