Question:
The volume of a circular iron rod of length 1 m is 3850 cm3. Find its diameter.
Solution:
Volume $=\pi \mathrm{r}^{2} \mathrm{~h}=3850 \mathrm{~cm}^{3}$
Height $=1 \mathrm{~m}=100 \mathrm{~cm}$
Now, radius, $r=\sqrt{\frac{3850}{\pi \times \mathrm{h}}}=\sqrt{\frac{3850 \times 7}{22 \times 100}}=1.75 \times 7=3.5 \mathrm{~cm}$
Volume $=\pi \mathrm{r}^{2} \mathrm{~h}=3850 \mathrm{~cm}^{3}$
Height $=1 \mathrm{~m}=100 \mathrm{~cm}$
Now, radius, $r=\sqrt{\frac{3850}{\pi \times \mathrm{h}}}=\sqrt{\frac{3850 \times 7}{22 \times 100}}=1.75 \times 7=3.5 \mathrm{~cm}$
$\therefore$ Diameter $=2$ (radius) $=2 \times 3.5=7 \mathrm{~cm}$
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