LESSON 3 DISTANCE CALCULATION DIRECT DISTANCE INDIRECT DISTANCE

LESSON 3: DISTANCE CALCULATION DIRECT DISTANCE INDIRECT DISTANCE

DIRECT DISTANCE IS ASKED OF A STRAIGHT LINE DISTANCE ON THE MAP BETWEEN TWO LOCATIONS. IT CAN BE CALCULATED WITH THE HELP OF A SCALE/ RULER IN CENTIMETRES THEN CONVERTED TO KILOMETRES.

Another method to calculate direct distance MARK 2 POINTS BETWEEN WHICH THE DISTANCE IS TO BE FOUND. MEASURE WITH A DIVIDER/ STRING. PLACE TH STRING /DIVIDER ON THE SCALE AND FIND THE DISTANCE IN CENTIMETRES. CONVERT TO KILOMETRES BASED ON THE SCALE OF THE MAP PROVIDED.

Example of direct distance calculation DISTANCE BETWEEN 2 POINTS ON THE MAP IS 2 CENTIMETRES. GROUND DISTANCE IS TO BE CALCULATED. THE GIVEN SCALE OF THE MAP IS 1 CENTIMETRE TO 12 KILOMETRE [THIS SCALE WOULD BE GIVEN AT THE BOTTOM OF THE TOPO MAP NEAR THE DRAWN LINEAR SCALE]

THE CALCULATION 1 CM ON THE MAP REPRESENTS 12 KM THEREFORE 2 CM REPRESENTS 12 X 2=24 KM THE GROUND DISTANCE BETWEEN THE TWO POINTS ON THE MAP IS 24 KM.

INDIRECT DISTANCES ARE ASKED OF IRREGULAR OR CURVED LINES ON THE MAP, OF RIVER COUSES, RAILWAY LINES, ETC.

FINDING INDIRECT DISTANCE TAKE A STRING[A 20 CM STRING IS PROVIDED IN THE EXAM HALL WITH THE TOPO MAP] SPREAD THE STRING ALONG THE CURVED LINE FOLLOWING EACH CURVE TILL THE LAST POINT. MARK THE STARTING AND THE ENDING POINT ON THE STRING.

CALCULATING THE INDIRECT DISTANCE STRETCH THE STRING ALONG THE SCALE/ RULER TO FIND OUT THE LENGTH BETWEEN THE 2 POINTS MARKED ON IT. CONVERT THE CMS INTO KILOMETRES, BASED ON THE SCALE OF THE MAP PROVIDED.