Lesson 3: Answers/hints for exercises


  1. Use an Earth globe to determine the latitude and longitude, to the nearest degree, of
    1. New York, N.Y.
      41°N 73°W
    2. Beijing, China
      40°N 114°E
    3. Sydney, Australia
      44°S 152°E
  2. Determine the distance in nautical miles from 0°N 28°41'E to 0°N 16°38'W.
    The points are on the equator, so the distance between them is measured along the equator. One minute of arc represents one nautical mile. In minutes,
    distance = 28°41' - (-16°38') = 28°41' + 16°38'
    = 44°79' = 44 * 60 + 79 minutes = 2719 minutes
    So the distance is 2719 nautical miles, i.e.
    approximately 2719 * 1.154, or 3137.73, miles
  3. Is there any place on Earth that can be located uniquely by its latitude(i.e. without specifying a second coordinate)?
    The North Pole, at 90 degrees north latitude and
    the South Pole, at 90 degrees south latitude
  4. Is there any place on Earth that can be located uniquely by its longitude(i.e. without specifying a second coordinate)?
    No. Every meridian contains infinitely many points. A second coordinate, e.g. latitude, is needed to locate a particular point.
  5. Use a world globe to determine the shortest route from San Francisco to Tokyo. Describe the route in terms of place names, bodies of water, etc.
    West by northwest across the Pacific to a northern most point, and midpoint, at approximately 50°N 165°W, then west by southwest, on a path symmetric to the first half, to Tokyo. The northernmost portion of the path is close to, and south of, the Aleutian Islands.
  6. Using latitude and longitude to approximate its extremities, describe the portion of Earth that is diametrically opposite the contiguous forty-eight states of the U.S.A.
    7. Representing extreme points in Maine, Washington, California, Texas and California as, respectively, 47°N 53°E, 48°N 124°W, 32°N 117°W, 26°N 98°W and 25°N 81°W, the corresponding diametrically opposite points are at 47°S (180-53)°S or 47°S 127°E, and, similarly, 48°S 56°E, 32°S 63°E, 26°S 82°E and 25°S 99°E. The region, mostly a part of the Indian Ocean, includes the western extremity of Australia in the East.
  7. What would be the effect on global climate if Earth's axis of rotation were perpendicular to the plane of rotation rather than tipped at an angle of 23.5° with that plane?
    The tilt of the axis is the primary cause of seasonal differences. Apparently the effect of differences in distance from Sun is negligible. If the axis were always perpendicular to the plane of orbit, then at each point on Earth, every day would be the same throughout the year. There would be no days of equinox or solstice. The poles would be in perpetual winter, the equator in perpetual mid-summer.

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Materials developed by-
Wm. Rundberg
College of San Mateo
1700 West Hillsdale Blvd
San Mateo, Ca. 94402
650.574.6258
rundberg@smcccd.cc.ca.us