Hemisphere Cylinder
1. **Problem Statement:**
A hemispherical bowl of radius 7 cm is full of water. We need to find the area of the wet surface (the inner surface of the hemisphere in contact with water).
Then, the water is emptied into a hollow cylinder with diameter 8 cm and height 7 cm. We must determine if the water will overflow the cylinder.
2. **Formulas and Important Rules:**
- Surface area of a hemisphere (curved surface only) is given by $$2\pi r^2$$.
- Volume of a hemisphere is $$\frac{2}{3}\pi r^3$$.
- Volume of a cylinder is $$\pi r^2 h$$.
- Diameter $$d$$ relates to radius $$r$$ by $$r=\frac{d}{2}$$.
3. **Step 1: Calculate the wet surface area of the hemisphere**
Given radius $$r=7$$ cm,
$$\text{Wet surface area} = 2\pi r^2 = 2\pi (7)^2 = 2\pi \times 49 = 98\pi \text{ cm}^2$$.
4. **Step 2: Calculate the volume of water in the hemisphere**
$$V_{hemisphere} = \frac{2}{3}\pi r^3 = \frac{2}{3}\pi (7)^3 = \frac{2}{3}\pi \times 343 = \frac{686}{3}\pi \text{ cm}^3$$.
5. **Step 3: Calculate the volume of the cylinder**
Diameter $$d=8$$ cm, so radius $$r=\frac{8}{2}=4$$ cm, height $$h=7$$ cm.
$$V_{cylinder} = \pi r^2 h = \pi (4)^2 \times 7 = \pi \times 16 \times 7 = 112\pi \text{ cm}^3$$.
6. **Step 4: Compare volumes to check for overflow**
Volume of water $$= \frac{686}{3}\pi \approx 228.67\pi$$ cm³.
Volume of cylinder $$= 112\pi$$ cm³.
Since $$228.67\pi > 112\pi$$, the water volume is greater than the cylinder volume.
7. **Conclusion:**
The water will overflow when poured into the cylinder because the volume of water from the hemisphere exceeds the cylinder's capacity.
**Final answers:**
- Wet surface area of hemisphere: $$98\pi \approx 307.88$$ cm².
- Water will overflow the cylinder.