Question

what is the approximate gradient along line bd?
a) 100 m/km
b) 150 m/km
c) 25 m/km
d) 50 m/km

Explanation:

Step1: Determine the elevation difference

The elevation at point B is \(100\) meters and at point D is \(50\) meters.
The elevation difference \(\Delta h=100 - 50=50\) meters.

Step2: Measure the map - distance

Using the scale bar, the map - distance between B and D is approximately \(1\) km.

Step3: Calculate the gradient

The formula for gradient \(G=\frac{\Delta h}{d}\), where \(\Delta h\) is the elevation difference and \(d\) is the horizontal distance.
Substituting \(\Delta h = 50\) meters and \(d = 1\) km into the formula, we get \(G=\frac{50\space m}{1\space km}=50\space m/km\).

Answer:

D. \(50\space m/km\)