Question

An observer standing 30 m away from the tree on a level surface and measures the height of the tree with the help of Ravialtimeter and records 15.60 to the top of the tree (top reading) and 1.70 to the bottom of the tree (bottom reading) on 30 m scale. The total height of the trees is ______________.

• A. 20.20 m
• B. 17.30 m
• C. 15.60 m
• D. 1.40 m

Hint:

On level ground, always add the top and bottom readings of an altimeter. If the base of the tree is above your eye level (sloping ground), you subtract the bottom reading from the top reading.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The question asks for the total height of a tree based on altimeter readings taken from a fixed horizontal distance on level ground.
Height measurement of standing trees is a fundamental task in forest mensuration, often using instruments like the Ravi Altimeter or Abney Level.

Step 2: Key Formula or Approach:
For an observer on a level surface:
1. If the top of the tree is above the eye level and the bottom is below the eye level, the total height is the sum of the elevation and depression readings.
2. Total Height ($H$) = Top Reading ($a$) + Bottom Reading ($b$).

Step 3: Detailed Explanation:

• The observer is at a horizontal distance ($D$) of 30 m. The Ravi Altimeter is calibrated for specific distances (usually 20 m or 30 m scales).

• The reading to the top of the tree ($a$) represents the height from the horizontal eye level to the tree tip, which is 15.60 units (meters on the 30 m scale).

• The reading to the bottom of the tree ($b$) represents the vertical distance from the horizontal eye level down to the base of the tree, which is 1.70 m.

• Since the ground is level, the total height of the tree is the sum of these two vertical components:
\[ H = 15.60\text{ m} + 1.70\text{ m} \]
\[ H = 17.30\text{ m} \]

Step 4: Final Answer:
The total height of the tree is 17.30 m.