Volume Revolution
1. **State the problem:**
We are given two curves: $x=2\sqrt{y}$ and $y=2\sqrt{x}$.
We need to find the volume generated by revolving the area enclosed by these curves about the x-axis.
2. **Find the points of intersection:**
Rewrite $x=2\sqrt{y}\implies \sqrt{y}=\frac{x}{2}\implies y=\frac{x^2}{4}$.
Given $y=2\sqrt{x}$, square both sides to get $y^2=4x$.
To find the intersection, substitute $y=\frac{x^2}{4}$ into $y=2\sqrt{x}$:
$$\frac{x^2}{4} = 2\sqrt{x}$$
Multiply both sides by 4:
$$x^2 = 8\sqrt{x}$$
Rewrite $\sqrt{x}$ as $x^{1/2}$:
$$x^2 = 8x^{1/2}$$
Divide both sides by $x^{1/2}$ (assuming $x>0$):
$$x^{3/2} = 8$$
Raise both sides to the power $\frac{2}{3}$:
$$x = 8^{2/3} = (2^3)^{2/3} = 2^{2} = 4$$
Substitute back to get $y$:
$$y = 2 \sqrt{4} = 2 \times 2 = 4$$
So the curves intersect at points $(0,0)$ and $(4,4)$.
3. **Set up the volume integral:**
The volume generated by revolving around the x-axis is found by the washer method:
$$V = \pi \int_0^4 \left[(\text{outer radius})^2 - (\text{inner radius})^2\right] dx$$
In terms of $x$, the outer radius is the y-value of the upper curve from the x-axis, and inner radius is the y-value of the lower curve.
From the given curves:
- Curve 1: $y=\frac{x^2}{4}$
- Curve 2: $y=2\sqrt{x}$
Between $x=0$ and $x=4$, $y=2\sqrt{x} \geq \frac{x^2}{4}$.
So,
$$V = \pi \int_0^{4} \left[(2\sqrt{x})^2 - \left(\frac{x^2}{4}\right)^2\right] dx = \pi \int_0^{4} \left[4x - \frac{x^4}{16}\right] dx$$
4. **Evaluate the integral:**
Calculate separately:
$$\int_0^{4} 4x \, dx = 4 \times \frac{x^2}{2} \bigg|_0^4 = 4 \times \frac{16}{2} = 4 \times 8 = 32$$
$$\int_0^{4} \frac{x^4}{16} \, dx = \frac{1}{16} \times \frac{x^5}{5} \bigg|_0^4 = \frac{1}{16} \times \frac{1024}{5} = \frac{1024}{80} = \frac{128}{10} = 12.8$$
So,
$$V = \pi (32 - 12.8) = \pi \times 19.2 = 19.2\pi$$
5. **Final answer:**
$$\boxed{19.2\pi}$$