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The correct answer is an overhanging cliff.

Contour lines can cross one another on a map only in the case of an overhanging cliff. In such a scenario, the contour lines may overlap to represent the vertical extent of the cliff. In other cases, such as ridges or valleys, contour lines do not cross each other.

In a whole circle bearing system, N 25° 15' W corresponds to 335° 15'.

Here’s how you can convert it:

• North 25° 15' West means 25° 15' west of the north direction.
• To find the whole circle bearing, you subtract this angle from 360°.

Thus,

360°−25°15′=334°45′360° - 25° 15' = 334° 45'360°−25°15′=334°45′

Therefore, N 25° 15' W corresponds to 334° 45' in a whole circle bearing system. It seems like there may have been a mistake in the provided options.

The difference is length between the arc and the subtended chord on the surface of the earth for a distance of 18.2 km is only 10 mm.

This is a common approximation used in surveying. For distances up to about 20 km, the difference between the arc length and the chord length on the Earth's surface is negligible and can be considered as approximately 1 cm or 10 mm.

The correct answer is all of these.

The contour interval depends on:

• Purpose and extent of survey: The interval may be adjusted based on the specific needs of the survey and the area being surveyed.
• Scale of map: Larger scale maps typically use smaller contour intervals to provide more detail.
• Nature of the ground: Steeper or more varied terrain may require different contour intervals to accurately represent the landscape.

The correct answer is by graphical method.

In the indirect method of contouring, the best method of interpolation of contours is typically the graphical method. This method involves drawing smooth curves between known contour lines to estimate the intermediate contours, providing a more accurate and visually coherent representation of the terrain.

To find the back bearing from the fore bearing, you add or subtract 180° from the fore bearing.

For the fore bearing of N 26° 35' W:

• Adding 180° to the fore bearing:
  • Convert the bearing to a whole circle bearing: N 26° 35' W is 360° - 26° 35' = 333° 25'.
  • Add 180°: 333° 25' + 180° = 513° 25'.
  • Adjust to within 360°: 513° 25' - 360° = 153° 25'.

Converting back to a quadrant bearing:

• 153° 25' corresponds to S 26° 35' E.

Thus, the back bearing is S 26° 35' E.

The expression v2gR\dfrac{v^2}{gR}gRv2​ is called the centrifugal ratio.

This formula represents the ratio of the centrifugal force to the gravitational force acting on a vehicle or object moving in a circular path.

The correct answer is first quadrant.

In the first quadrant (0° to 90°) of a whole circle bearing system, both the latitude (northing) and departure (easting) of a traverse line are positive.

The error that is not completely eliminated in reciprocal levelling is:

error due to refraction

Reciprocal levelling helps to reduce errors due to curvature and refraction, but it cannot completely eliminate the effect of refraction, which can still introduce some residual error.

The relation between the radius \( R \) of the curve and the degree of curve \( D \), given that the chord length is 30 meters, can be found using the formula for the degree of curve in terms of the radius and chord length. The formula is:

\[ D = \dfrac{180 \times 30}{\pi \times R} \]

Here, \( D \) is the degree of the curve, \( R \) is the radius, and the chord length is 30 meters. Rearranging this formula to solve for \( R \), we get:

\[ R = \dfrac{180 \times 30}{\pi \times D} \]

Simplifying:

\[ R = \dfrac{5400}{\pi \times D} \]

Using the approximate value of \(\pi \approx 3.14\), this simplifies further to:

\[ R \approx \dfrac{5400}{3.14 \times D} \approx \dfrac{1720}{D} \]

So the correct relation is:

\[ R = \dfrac{1720}{D} \]