Beginning of Essay
Today's society relies heavily on an invention taken for granted: radar. Just about everybody uses radar, whether they realize it or not. Tens of thousands of lives rely on the precision and speed of radar to guide their plane through the skies unscathed. Other ....

Middle of Essay
.... their lifetime. Radar works much like an echo. In an echo, a sound is sent out in all directions. When the sound waves find an object, such as a cliff face, they will bounce back to the source of the echo. If you count the number of seconds from when the sound was made to when the sound was heard, you can figure out the distance the sound had to travel. The formula is: (S/2) X 1100 = D (Half of the total time times 1100 feet per second equals the distance from the origin to the reflection point) Of course, radar is a much more complicated system than just somebody shouting and listening for the echo. In fact, modern radar listens not only f ....