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geography - Coggle Diagram
geography
mapping skills
AR and GR
AR - area reference. given by 4 digits. the easting followed by the nothing e.g. a = AR 3652 b = AR 3852
GR - grid reference is given by 6 digits, which are the same as the AR except with extra number for easting and northing that shows how far across or up the square a point is (on a scale of 0-9) e.g. a = GR 365528 b = GR 388522 c = GR 400537
as each is an estimate, small allowance is made for error in most cases
if asked for a GR of an area, like the sports field pick a spot in the middle and provide a reference such as GR 395508
longitude and latitude
Australia is in the southern and eastern hemispheres. therefore, any place in Australia must have a latitude that is south and a longitude that is east
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longitude is measured in degrees and minutes east or west of the prime meridian (0 degrees longitude0
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in the Australia this would always be 34 degrees S, etc "top right of the grid"
a mid point between 34 degrees S and 35 degrees S would be 34 degrees and 30 minutes. this is written as 34 degrees 30' S
these lines aren't drawn on maps
point A is about half way between 35 degrees and 35 degrees 30'S , therefore its latitude coordinate would be about 35 degrees 15' S
when you combine these two coordinates, the position of point 'A' is written as: 35 degrees 15'S 147 degrees 45'S
point A is about half way between 147 degrees 30'E and 148 degrees E. therefore its longitude coordinate would be about 47 degrees 45'E
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scale
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scale is shown using a linear method, or a ratio method
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as 50 000cm isn't very useful in the real world, we change it like this: 1 cm = 500m or 1cm = 0.5 km
if the distance between two points on a map is 8.5cm, and the scale is 1:50 000, the real distance would be 8.5 x 500 m = 4250m = 4.25 km
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time, distance and speed
Distance: the distance between two points on a map can be found by first measuring the distance shown on the map and then converting it from centimetres to kilometres using the scale
time and speed: when working with topographic maps you may be required to calculate how long it would take to travel a specific distance or the speed someone is travelling.
how long would it take to travel 30km at 80 km/h
- step1: divide 60 (min) by 80 (speed) = 0.75
- step 2: multiply the time taken to travel 1 km by the distance to be travelled.
- 0.75 x 30 km = 22.5