Mapwork Calculations

Gradient, cross-sections, distance

Gradient and Cross-Sections

In Grade 9 mapwork, you calculate gradient (steepness), measure distances and draw cross-sections. Gradient = vertical distance ÷ horizontal distance. Scale helps convert map distances to real distances.

Example

Gradient Calculation

Two points on a 1:50 000 map: • Point A: 1200 m, Point B: 800 m • Map distance: 4 cm → Real: 4 × 500 m = 2000 m Gradient = (1200 − 800) ÷ 2000 = 400 ÷ 2000 = 1:5 (very steep!)

Note

Remember

For SA 1:50 000 maps: 1 cm = 500 m. Gradient written as 1:x. Steep = small number (1:5). Gentle = large number (1:100). Cross-sections show the shape of land along a line.

Key Vocabulary

GradientThe steepness of a slope (vertical ÷ horizontal)

Cross-sectionA diagram showing the shape of land along a line

Vertical distanceThe difference in height between two points

Horizontal distanceThe flat distance between two points

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Gradient

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