Mathematics and Society - OS X Lion Server

In It's A Long Shot triangulation is used to measure the distance to the Moon.Radar, coined from the words RAdio Qetection ~d ~anging, has also been used to measurethe distance to the Moon. What is radar and how does it work? A radar set sends out aradio signal which will bounce off an object and return to the station a bit weaker.Radio signals travel through space at the speed of light, 300,000 km each second. Bymeasuring the time it takes a radio signal to travel to a target and back, it is possibleto determine the distance a target is from the radar set.Exercises:1) The U.S. Army Signal Corps first sent a radio signal to the Moon in 1946. It took2.5 seconds for the signal to travel out, bounce off the Moon and return.Find the distance to the Moon.2) In 1961 radar waves were first bounced from the surface of Venus. When Venus isclosest to the Earth the round trip time for the signal is about 280 seconds. Howclose is Venus to Earth?3) In the activity It's A Great systemthe distances in astronomical unitsof the planets from the Sun wereestablished. These distances aregiven in the table to the right.Use the result from problem #2 andthe information in the table tohelp you answer these questions.a) In astronomical units how faris Venus from Earth when it isclosest to Earth?b) How far is the Earth from thes~n in.astronomical urtits? Inkilometres?c) Find the distance in kilometresfrom each planet to the Sun.Distance from thePlanets sun in a. u.Mercury .39Venus .72Earth 1Mars 1.52Jupiter 5.20Saturn 9.54Uranus 19.18Neptune 30.06Pluto 39.52Can radar be used to accurately measure the distance to the Sun? So far scientistshave been unsuccessful. Since the Sun is composed mainly of hot gases, it is a softtarget and does not reflect the radio waves. However, by using radar to measuretthedistance to Venus and applying this to the solar system model in It's A Great System wecan determine the distance to the Sun."'1M ArJ 0OLD SOFTIE.00 """IDEA FROM:In Orbit, Probing the Natural World, Level III, Intermediate Science Curriculum StudyPermission to use granted by Silver Burdett General Learning Corporation97