Question

Linear
Draw scale to read 400 meters and 100 meters
on primary and secondary arvision suspedively.
Take RF = 1:13000​

Answer 1

Representing scales: The proportion between the drawing and the map can be represented by two ways as follows:

a) Scale: – 1cm ≡ 1m or 1cm ≡ 100cm or 1:100

b) Representative Fraction: – (RF) 1/100 is the ratio between the size of the drawing and the object.

Types of Scales and their constructions:

When an unusual proportion is to be adopted and when the ready made scales are not available then the required scale is to be constructed on the drawing sheet itself. To construct the scale the data required is 1) the R.F of the scale 2) The units which it has to represent i.e. millimetres or centimetres or metres or kilometres in M.K.S or inches or feet or yards or miles in F.P.S) The maximum length which it should measure. If the maximum length is not given, some suitable length can be assumed.

The maximum length of the scale to be constructed on the drawing sheet =

R.F X maximum length the scale should measure.

This should be generally of 15 to 20 cms length.

Table: Metric Units Table: FPS Units

1 Kilometre (km) =10 Hecta metres (hm) 1 Mile =8 Furlongs

1 Hectametere(hm) =10 Decametres(dam)or 0.1km 1 Furlong =220 Yards

1 Decametre(dam) =10 Metres (m) or 0.1hm 1Yard =3 Feet

1 Metre(m) =10Decimetres(dm) or 0.1dam 1 Feet =12 Inches

1 Decimetre(dm) =10 Centimetres(cm) or 0.1m

1 Centimetre(cm) =10 Millimetres (mm) or 0.1dm

The various types of scales used in practice are 1. Plain or Simple scales, 2. Diagonal scales, 3. Vernier scales, 4. Comparative scales and 5. Scale of chords.