a) Physical measuring tape
The physical form of the measuring tape in the form of a ribbon that has the scale (unit of measurement). The units of measurement used is cm with the smallest unit of measurement in millimeters. Measuring tape can be either tape or ribbon around the diameter (phi band).
b) Basic Work
Measuring tape wrapped around a tree trunk as high as 1.30 m (Figure 32). The results of measurements around the circumference when using tape and if using a diameter tape is the result of its size is the diameter. Scale the size of the diameter tape is k = k / π
Figure 32. How to use a measuring tape
Sample calculation:
(a) Measurement with tape around
The measurement results obtained trunk circumference of 125 cm. What is the diameter of the tree trunk?
Thread!
The calculation of stem diameter using a conversion formula:
In the field, often conventional computation is performed by dividing the circumference 3 of the measurement results.
The conventional way will produce a diameter greater than the conversion formula, which amounted to 1.89 cm. This value is derived from a reduced diameter to diameter calculation result of conventional conversion calculation results, ie 41.67 cm – 39.77 cm. In addition, it can be concluded is the diameter measurement error of conventional calculation results will be enlarged if the trunk circumference measured greater. Instead the error will be smaller, if the circumference of the trunk which measured less.
(b) Measurement with a diameter tape (phi band)
The measurement results obtained with phi-tire diameter of 75 cm. Thus, trunk diameter measured was 75 cm.
(c) Error measuring diameter or circumference trunk
Measurement error due to the position of the ribbon coiled rod are not parallel to or the same height to the plane. Thus winding the tape is not a circle, but will form an ellipse. Below given formula measuring errors diameter or circumference of the tree trunk.
For the measurement of the circumference (Figure 33).
Figure 33. Errors with tape measure around