Harvard Test Question and Answer

A common question asked on the Harvard test is “Why are manhole covers round?” The best possible answer is “because they do not fall in”. Also, one may explain that covers of any other shape have varying diameters and therefore would fall through manholes. Thus, circular manholes remain in their places despite the heavy road traffic running over them. During their manufacture, pouring hot metal in a round mould is much easier than in a mould with sharp corners like square or rectangular. Manholes are placed at various sewer pipe junctions so it is necessary to seal them tightly and circular manhole covers have smaller sized lip to rest upon. Additionally, it is easier to lift and roll circular covers because of their shapes while removing them from the topside of manholes.