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Radar is an abravation word: Ra stands for radio D for detection A for and R for ranging Radar designed to detect and track the presence of aircraft, missieles and other electronic technology. This system is similar with traffic control ground vehicles. The distance is calculated as given below Speed = Distance /Time

Physics explain the universe with its prporty

Social media is the most powerful in our world,but Most of African people Uses for other purposes. Africans we always affected by politics and backwardness.We do not know how social media is used for earning money online.As part of the world community every thing reaches after American, Asian, European and Australian.I do not understand why always late in technology, in my opinion leaders play a vital role in such development.African leaders,they live for their own purpose.