The hardness of different materials by Rockwell scale Lab Report

The hardness of different materials by Rockwell scale - Lab Report Example The obtained data is consistent to the hardness tester calibrations. The experiment was done through performing the different tests on metals having the hardness that is known. There was a close similarity between the experimental values and the published values of hardness. From the results, it is evidenced that cast iron was the hardest material followed by 1018 steel, brass and lastly aluminium. Aluminium is considered to be relatively durable, soft, lightweight, malleable and ductile metal having an appearance that ranges from silver towards dull grey. Its appearance is dependent on the roughness surface. Aluminium is nonmagnetic and has a low potential for ignition. An aluminium fresh field acts as a good visible light reflector and a delightful reflector of far and medium infrared radiations. Pure aluminium has the yield strength of 7 to 11 MPa whereas its alloy has a yield strength of about 200MPa-600MPa. Studies conducted on the hardness of aluminium found out that aluminium ’s hardness is one third that of steel. This research argued out that aluminium was less hard than steel. The hardness of cast iron was close to that of 1018 steel.On the other hand, the hardness of brass changes according to its treatment and preparation and treatment. The hardness may reduce whenever the annealation is done at temperatures that are elevated (Zhang 2). The acoustic and malleability characteristics of brass make the metal be extremely useful in musical instruments such as trumpets (Anyalebechi 2).  

The positive and negative influences has televisions had on your Essay

The positive and negative influences has televisions had on your society - Essay Example Before television was around, news was reported by radio or in the next day's newspaper. There were no moving images. There was no opportunity to watch sport games or see presidents speak. There were real limitation to the amount of information a person at home could receive. Now, however, that has changed. Television lets us see the world like never before. We have a real opportunity to watch events develop in real time. The recent revolution in Egypt is a great example of this: it was possible to watch the square where protestors gathered night and day. Viewers could watch as the protestors were attacked by Molotov cocktails. These images brought the facts into vivid life. There are many other aspects which are positive. There are those who say television is bad for children. But scientific studies disagree. The economists found that television was especially positive for children in households where English wasn't the primary language and parents' education level was lower. "We do n't exactly know why that is, but a plausible interpretation is that the effect of television on cognitive development depends on what other kinds of activity television is substituting for," says Mr. Shapiro, 28. Growing up in the 1950s, Sonia Manzano, who plays Maria on "Sesame Street," was part of the first generation of children who watched television. Born in the South Bronx to Spanish-speaking Puerto Rican parents, she says that television "gave me a view of the world -- it gave me sort of a sense of what it was to be an American and what that was about." (Lahart). Television can open up whole new worlds to our children. There are trashy shows, no doubt, but there are also shows of substantial value. The difference is one of parenting. There is such a variety of kinds of programs, from documentaries to educational shows, that one can always learn something from television (Williams, 78). There are, however, a number of negative aspects to TV that are important to note. Televis ion can be a big waste of time. Many reality TV programs and entertainment news shows are glitzy and glamourous but impart no real knowledge. They are pointless and a waste of time. Many people spend hours in front of the TV when they should be getting exercise or acting in productive ways. Many children who watch TV can be negatively influenced by what they see. So many shows feature violent scenarios or the commission of crimes that children can get the wrong idea about how they should behave. They may learn to swear or drink alcohol by watching popular TV shows. Again, parenting is very important to help avoid this problem. Television can also be used to influence people in a negative way through propaganda. Television shows do not always show the truth and many people believe what they see on their screens. This is an unfortunate state of affairs. Governments try to use TV to manipulate their people, feeding them a diet of lies. Because TV images and stories can often seem so re al—which is why we watch so many dramas on our little screens—they can be incredibly powerful. Sometimes, there is not an intention behind the manipulation. Sometimes real important discussions are not seen to be entertaining enough, and are therefore kept off the air (Bourdieu, 3). Like with everything in life, there are good aspects of technology