LAB 2. WORKED EXAMPLES

Note: all numbers used are “made up”, but the techniques are correct.

 

1.      Find the length in meters of a minute of longitude on the map.

 

 

103o 17’ 30” W

103o 15’ W
 

 

 


23 cm
The difference in longitude between these two points is 2’ 30” or 2.5’. Using a ruler measure the distance between these two points – it is 23 cm. Use the graphic scale to determine the distance on the map (in meters) represented by 23 cm:

 


 

It is 2750 m. if 2.5’ = 2750 m, 1’ = 2750/2.5 = 1100 m.

 

2. At 600 N, one degree of longitude equals 55.8 km; one degree of latitude equals 111 km. Using these equivalents, calculate the distance in km between the following locations:

 

       600 00' 00" N             to           600 00' 00" N

     1330 22' 45" W                         1360 30' 50" W

 

LONGITUDE is changing. The amount of change is 30 8' 5". 10 = 55.8 km, therefore 30 8' 5" =

   3 x 55.8

+ 8 x 55.8/60

+ 5 x 55.8/3600

 

= 167.4 + 7.44 + 0.0775 =  174.9175 km = 174.918 km (round to 3 decimal places).

 

3.      What would be the distance in miles of the following distance where one longitude degree equals 45.2 miles:

40 20' 35" ? Answer =    4 x 45.2

                                  + 20 x 45.2/60

                                  + 35 x 45.2/3600

 

= 180.8 +  15.06666666667 +  0.4394444444444 =  196.3061111111 miles = 196.306 miles.

 

4. Give precise latitude and longitude coordinates of the following location:

 

3.5 cm

7.2 cm

From Q. 1 above, we know that 1’ longitude = 9.2 cm (23/2.5). Therefore the longitude will be 103o 15’ +

7.2/9.2 x 1’ or 103o 15’ + 7.2/9.2 x 60”

= 103o 15’ +  47” = 103o 15’ 47” W (Round to nearest second).

 

Let’s assume we have already calculated that 1’ of latitude = 11.5 cm on this map. Therefore, the latitude of the point is:

29o 15’ + 3.5/11.5 x 1’ or 29o 15’ + 3.5/11.5 x 60”

= 29o 15’ +  18” = 29o 15’ 18” N (Round to nearest second).

 

5. Give the 6-digit UTM grid reference for the following location:

3238000

3237000

668000

3/10 of a grid square

8/10 of a grid square

669000
 

 


The actual UTM reference for the point is 668800 m east, 3237300 m north. By convention, for a 6-digit UTM reference this is written as 688373 (note that the easting is always given first).

 

6. What is found at the following UTM grid reference: 697379

 

697

379

 

 

 

 

The answer is a cave.

 

7. How many kilometers a) east and b) north are between UTM references 123456 and 333777?

 

We know that two zeros have been left off of these UTM references; we must return the two zeros to calculate the distances:

 

a) easting separation = 33300 -12300 m = 21000 m = 21 km.

b) northing separation = 77700 – 45600 m = 32100 m = 32.1 km.