Question

The distance between two points on the map is 1.25 cm and the corresponding distance on the ground is 5.0 kms. Find out the R.F. and draw a plain scale for the map.

[Hint: Map distance = 1.25 cm
Ground distance = 5 km or 5 × 1,00,000 = 5,00,000 cm
∴ R.F. = `(1.25)/(5,00,000) = 1/(4,00,000)]`

Answer 1

Given: Map distance = 1.25 cm

Ground distance = 5.0 km = 5 × 100,000 = 500,000 cm.

R.F. = `(1.25)/(5,00,000) = 1/(4,00,000)`

Let’s take 18 cm as the convenient map length.

Ground distance = Map length × Representative value

= 18 × 400,000

= 72,00,000 cm

Convert to kilometers: `(72,00,000)/(1,00,000) = 72` km

So, 18 cm on map = 72 km on ground

Drawing the scale: 

Draw a line 18 cm long

Divide it into 6 equal parts, each = 12 km

Subdivide the first part into 6 small divisions, each = 2 km

Labelling:

On the right of 0: 0, 12, 24, 36, 48, 60, 72 km

On the left of 0: 2, 4, 6, 8, 10, 12 km (in reverse)