## 246. Math Puzzle $11 / 85$

A hollow round ceiling support in a large bakery is loaded with 28 tons. The outer diameter of the support is 145 millimeters, and the clear width, i.e., the inner diameter, is 115 millimeters.

What is the load per square centimeter of the cross-sectional area?
Calculation of the annular area:

$$
A=\frac{\pi}{4}\left(d_{2}^{2}-d_{1}^{2}\right)=\frac{\pi}{4}\left(14.5^{2}-11.5^{2}\right) \mathrm{cm}^{2}=61.26 \mathrm{~cm}^{2}
$$

$28000 \mathrm{~kg}: 61.26 \mathrm{~cm}^{2}=457.06 \mathrm{~kg} / \mathrm{cm}^{2}$.

Each $\mathrm{cm}^{2}$ of cross-sectional area is loaded with a mass of $457 \mathrm{~kg}$. We also considered $4483 \mathrm{N} / \mathrm{cm}^{2}$.