Laura Gómez, known as “LauriMathTeacher” on social media, is a popular math teacher on TikTok, where she has 1.7 million followers and more than 121 million “likes” on her videos.
In one of these videos, Laura explains why manhole covers are round and does so with the help of mathematics.
Manhole Covers Aren’t Round for No Reason
Manhole covers are part of the urban landscape of any town or city; in fact, there are so many of them and we see them so often that hardly anyone stops to think about them, much less why they have a circular shape, but there is an answer to the latter.
The explanation is unveiled on Laura Gómez’s TikTok channel and, of course, she uses mathematics to explain it. “The circle is the only figure that cannot fall inside itself,” Laura explains.
@laurimathteacher Why are manhole covers usually round? 👩🏼🏫✌🏼
♬ Carmen Habanera, classical opera(1283412) – perfectpanda
She clarifies that “If the cover were square, rectangular, or triangular, when you move it, at some angle it would surely slip through the opening, but the circle, no matter what angle you hold it at, will never slip through its own opening.”
Naturally, this is extremely important because beneath these covers are often fairly deep tunnels, and it would be very dangerous for someone to fall in if the cover failed to perform its function and sank.
By being circular, it is guaranteed that it will not slip into the tunnel, not even when a vehicle passes overhead and has to bear a lot of weight.
Moreover, Laura notes that the circular shape offers additional advantages for manhole covers: “When it comes to transporting them, it’s much easier to move them by rolling. Imagine having to move a square iron piece. Things get complicated.”
Another advantage is that they “withstand ground pressure better because the force is distributed uniformly” and Laura ends the video with one final benefit: “No matter how they are oriented when placed, they always fit.”
Images | TikTok (@LauriMathTeacher) and Unsplash
