Sharp Object’s and why are we afraid of them  

Steven A Sosa Alvarado           

     In an article that I found of physics it talks about how sharp objects can cut, pierce, and penetrate much more easily than others blunt objects even if the force is the applied is the same. This article interest me because at first I thought that force could have something to do with it but as it turns out the article says that it has to do with precision, pressure(force in which it acts upon) since the force applied on the objects is distribute among it but when it has to do with a sharp or pointy object the force is applied to the tip or sharp edge. The article gives an example with a needle and a nail. Even though the same amount of force is applied in both cases the needle has more precision then the nail and this is because of the force distribution mention earlier. This article made me think if an object was sharp and pointy enough could it be able to penetrate concrete or even steel or iron with very least force? Well with the information provided from the article I could say it could but it could have its exception depending on the size and force applied to the object. Similarly does the action of a force depend on whether it is distributed over a square centimeter or concentrated on the hundredth of a millimeter? The article also mentions that Skies easily take us across fresh snow; without them we fall through. Why? On skies the weight of your body is distributed over a much greater area. The article says that For the same reason horses used in marshlands are shod in a special fashion giving them a wider supporting area and lessening the pressure exerted per square centimeter. For the same reason people take similar precautions when they want to cross a bog or thin ice, often crawling to distribute their weight over a greater area. Finally, the article says that tanks and caterpillars tractors don’t get stuck in loose ground, although they are very heavy, again because their weight is distributed over a rather great supporting area. An eight-ton tractor exerts a pressure of only 600 grams per square centimeter. There are caterpillars, which exert a pressure of only 160 grams per cm square despite a two-ton load, which makes for the easy crossing of peat bogs and sand-beaches. Here it is a large supporting area, which gives the advantage, whereas in the case of the needle it is the other way round.  This all shows that a sharpened edge pierces things only because it has a very minute area for the force to act upon. This is why a sharp knife cuts better than a blunt one; the force is concentrated on a smaller area of the knife edge. To sum up: sharp objects prick and cut well, because much pressure is concentrated on their points and edges. Now thanks to this article I understand much better how force works on sharp objects. Also understand how sharp objects work on other objects.