For some one who doesn’t know what is Manhole cover, then, it’s a covering over the manholes, which can be removed and fitted easily. Any one could see them wherever the underground drainage passes near by your house or road.
Now the question is, why these manhole covers are round shaped!!! When I googled the shape of manhole covers, its mostly in round in shape. Also have got some images of the Rectangle and triangle shaped covers! But mostly in round shaped. There are many theories revolving around! Lets see some glimpses of that!
1) Manhole covers are round because the manholes are round.
2) Only round manhole covers will not fall in to the man hole
3)Heavy, round manhole covers are easier for one person to move by rolling.
4) You also don't have to "align" a manhole cover to its hole. Any orientation of the cover will do this.
5) Round manhole covers are easier to manufacture.§ Animals dig round holes, so it natural for humans too to do the same.
6) If any other shapes of sharp corners are followed then the sharp corners will pop up and have a possibility of hurting the car tires and humans!
7) The tunnels are pipes so its easier to go with the whole theme or circularity
8) If you stress test an a circle you will find that the circle dissipates the stress more evently at all points.
8) When you heat metals, they expand. Assume that you choose any shape other than circle, when they expand you can not know which parts becomes longer than other parts. But with circles they expand (almost) uniformly. So even with expanding they are easier to remove and put back in. So when they expand they do not get stuck.
9) Circular man holes are easy to dig. Hence covers are also round.
So this means manholes are one of the few things in the universe that are absolutely goof proof. Now it time to know one more fact about these manholes cover. This question in one which was asked in Microsoft’s Interview. So don’t try to ignore. It may also fetch u a job in some other company too!! Good Luck friends!!!
