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2.1 Calculate the magnetic bearing of spot height 1200 (block H5) from trigonometrical station 203 in block G6 on the topographical map - NSC Geography - Question 2 - 2016 - Paper 2
Question 2
2.1 Calculate the magnetic bearing of spot height 1200 (block H5) from trigonometrical station 203 in block G6 on the topographical map. Formula: Magnetic bearing =... show full transcript
Worked Solution & Example Answer:2.1 Calculate the magnetic bearing of spot height 1200 (block H5) from trigonometrical station 203 in block G6 on the topographical map - NSC Geography - Question 2 - 2016 - Paper 2
Step 1
Calculate the magnetic bearing of spot height 1200 (block H5)
Answer
To find the magnetic bearing of spot height 1200, we follow these steps:
-
True Bearing:
- According to the formula, the true bearing is 223°.
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Difference in Years:
- Difference = 2016 - 2002 = 14 years.
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Mean Annual Change:
- The mean annual change is 11' W (west).
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Total Change:
- Total change = 14 years * 11' = 154' (2°34').
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Magnetic Declination for 2016:
- Magnetic declination is 26°50' W.
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Magnetic Bearing for 2016:
- Magnetic bearing = True bearing + Magnetic declination = 223° + 26°50' = 249°50'.
Step 2
Calculate the area of recreational area S on the topographical map in m²
Answer
The area can be calculated using the formula:
- Area = length (L) x breadth (B)
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Length (L):
- Taking the length as 0.7 km = 700 m
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Breadth (B):
- Taking the breadth as 0.5 km = 500 m.
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Calculating Area:
- Area = 700 m * 500 m = 350,000 m².
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Final Calculation:
- Putting this into a formula gives:
- Area = 350,000 m² + 250 m² = 87,500 m².
Step 3
Explain why it appears to be larger on the orthophoto map
Answer
The area of recreational area S on the topographical map is the same as that on the orthophoto map because they represent the same location. However, the orthophoto map is at a different scale:
- The scale of the orthophoto map is 1:10,000, while the scale of the topographical map is 1:50,000.
- This indicates that for every unit on the orthophoto map, the corresponding unit on the topographical map covers a larger distance, which makes the area appear larger on the orthophoto map.
Step 4
Calculate the average gradient between trigonometrical station 293 in block D6 and trigonometrical station 187 in block D7
Answer
To find the average gradient:
-
Vertical Interval (VI):
- VI = height of station 293 - height of station 187 = 468.9 m - 211.1 m = 257.8 m.
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Horizontal Equivalent (HE):
- Distance = 3.2 km = 3200 m.
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Gradient Calculation:
- Gradient = VI / HE = 257.8 m / 3200 m = 0.0806.
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Final gradient representation:
- The average gradient can be expressed as a ratio or percentage as well (e.g., 1:12.4 or 8.06%).