a device which uses radio waves to locate and tract objects.?

Answer 1

Sonar uses sound, leif, the answer is RADAR (not spelled Radar, it's an acronym, hence all Caps)

Answer 2

The 2012 is exactly that: a hoax! No respectable or responsible scientists are predicting any such events for 2012. Could youplease explain how a webbot could possibly detect a planet when telescopes can't? NASA hasn't detected any such object (see source below). The world has existed for over four billion years. Is it reasonable to expect that it will come to an end in less than four years? And all because of a Mayan calendar? Use some common sense. The most interesting astronomical events in 2012 will be an annular eclipse of the Sun on 2012 May 20, a total eclipse of the Sun on 2012 Nov 13, and a transit of the planet Venus across the face of the Sun on 2012 Jun 06. Scientists don't expect anything out of the ordinary to happen in the year 2012, or specifically on the date December 21, except for the solstice, which happens every year. None of the "predicted" happenings for 2012 hold up under close scrutiny. "Planet X" and "Nibiru" simply don't exist. The Mayan calendar ends a cycle, but there were no predictions of the end of the world. The Sun doesn't line up with the galactic centre; it's 6 degrees off. No asteroids or comets are actually predicted to hit Earth. All of this stuff was put together by crackpots in order to promote their books and TV shows, and shamelessly promoted by the History Channel. Don't take any of it seriously!

Answer 3

Sonar, aka Radar.

Answer 4

radar

Answer 5

metal detector?