In the previous segment we learned more about the units of measurement of length, SI unit of length, and the conversion of one unit of length to another.
In this segment, we will understand the different types of tools that are used to measure lengths, the common errors in measurement and the precautions necessary to avoid them.
What are the different types of length measuring tools?
- Ruler or Scale – A centimetre scale is used to measure the length of line segments in geometry, small objects like pencil, boxes, paper,
Similar to a centimetre scale, we have a meter scale which is 1 meter long. This is used to measure the length of larger objects like a chalkboard or a tile.
- Measuring tape – A Measuring tape is a coil of plastic or metal tape with graduations of meter, centimetre, millimetre and inch, just like in a meter scale. Being flexible and easy to carry, measuring tapes are used by tailors to measure the length of cloth, carpenters to measure the length of wood, construction workers to measure the length of a wall and so
Despite having different types of length measuring tools, there are 3 common errors involved while measuring lengths.
Errors in measurement and necessary precautions
(i) Improper placement of the scale
While measuring the length of a plane surface, we can often place our scale in a tilted position. This type of error can be avoided by ensuring that the scale is always kept exactly along the length that we are measuring.
Incorrect way Correct way
Comparing the proper and improper placement of the scale
Corners are not coincident
While taking the measurement, if the corners of the scale and objects do not match, then you will get an error in the measurement of length. So ensure that the corners of the scale and the object are coincident.
Incorrect way Correct way
The edge of a scale can often be broken which may lead to a demarcation of the length marking near it. This can introduce an error of around 1 millimetre or so.
To avoid this, we can measure our lengths starting from the 1 cm mark instead of zero. All you need to do now is subtract 1 cm from the length you measured. This ensures the actual length to be accurate.
Measuring from 1 centimetre of the scale
- Incorrect eye positioning
The position of our eye also plays an important role in measuring any length. Viewing the measurement at an angle can lead to improper measurements. To prevent this, always position your eye perpendicularly above the point of measurement.
