### Why manhole covers are round in shape then square and any other shape?

See Solution

**Because it wont fall into the hole.**

**But**then equilateral triangle shape will also not fall into the hall.

One more reason is that it is easy to role the cover to a distance then carry it.

More reasons why manhole covers are round:-

- It does not break the symmetry, like if a square cover is not parallel to the roads it will not look good.
- Its easy to cover it, you don’t have to worry about the orientation while putting it back.

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Charles says

Consider athread of length 10 mts…case 1: make a square with it…perimeter is 4a=10, so a =2.5m….therefore area a^2 =(2.5)^2=6.25 sq m….case 2: make a circle wit it..perimeter 2πr=2*3.14*r=10. So r=1.5923 …area of circle =π*r*r=3.14*1.5923*1.5923=7.961 sq. m…circular man hole allows more water flow inside….u can try other shapes also.

Eshaan says

Charles, ur answer is the most logical i have come across.. thankss, cheers

karthik says

why do you want to have a constant perimeter as criteria ? Since the main purpose of the manhole is to drain water constant area should be the criteria and we should consider the minimizing the volume/material. considering same thickness the same area, the volume required will be same so whatever the logic you explained doesnt convey the purpose

Seemon says

Ma holes are for man to enter and not for water to flow. Round is the perfect shape and the cover will not fall into the hole . In a square manhole, the cover can fall easily when placed in a diagonal manner, perpendicular to the ground.

motherf*cker says

@Douchebag..equilateral triangle can fall!

srk says

It is the perfect shap that cannont fall into hole in any angle