A ruler is a simple tool to measure length. However, the question of how to read a ruler in precise terms remains persistent among the masses.
Taking accurate measurements occupies immense significance in different domains of human civilization. Be it the discovery of the measuring copper rod in Indus Valley civilization to the loss of NASA’s $92 mn Mars Climate Orbiter in 1999 due to measurement conversion errors that caused computational complexities.
This makes reading basic measurements extremely important, right from using a ruler in formative years to attempting highly complex operations.
Moving in the same direction, here is a brief account to understand how to read different types of rulers.
What is a Ruler?
Before learning how to read a ruler, we must understand the basics of the core topic, i.e., the ruler.
In simple terms, it is a tool to draw lines and measure the basic dimensions (specifically length) of any object. It comes in various types, differing in material and length. For example, rulers are made of materials such as metal, wood, glass, or flexible plastic and are also based on systems such as yardsticks and line gauges.
It has profound uses, especially in the academic field, that too in studying mathematics. Although several interfaces, such as Math Playground, have simplified developing a thorough understanding of the subject, grasping some theoretical sections still requires traditional methods to master the fundamentals of math.
Before going with the basics of reading a ruler, let’s understand what ruler marking means.
Meaning of Ruler Marking
While using a ruler, you might have observed the lines of various sizes. These are called the ruler markings. They help in measuring any object in observable units. These lines of variable length facilitate scaling the minutest relevant dimension of an object.
The longer lines depict the major measurement units, and the smaller lines show the minor measuring units in the ruler. These divisions aid in improving accuracy in taking measurements.
To further facilitate the users in attempting measurements, certain fractional rulers have also been made available. They depict values in fractions such as ⅜ on a ruler.
Now let’s learn how to read a ruler comprehensively.
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How to Read a Metric Ruler?
A metric ruler is a tool to measure the length in centimeters and millimeters. It is used across the world, with few exceptions of countries from American continents that use an imperial scale, having inch-based rulers.
The long lines show the centimeters, and the short lines in between the longer ones are a measure of a mm on a ruler. These markings on the ruler are depicted in the following figure.
To measure a length using a metric ruler, here are the few steps mentioned below:
- Adjust the 0 with the one end of the object or place it at the starting point of the target length.
- Now carefully observe the other end of the object, bring the ruler to it, and find the cm or mm line on the ruler that aligns with it.
- Calculate the total gap between the 0 and endpoints by considering the long and the short lines to get an accurate measure of the object’s dimension.
As the measurement of a millimeter can inflict error in the final result, it is advisable to stay accurate in going through the above steps to avoid negligible faults. Now let’s understand what an inch ruler is and how to read it.
How to Read an Inch Ruler?
Also called the imperial scale ruler, it measures the length in inches and similar smaller units and is widely used in the US and other countries.
A standard inch ruler has 12 lines for measuring the inches, which are further divided into smaller divisions denoted by shorter lines.
The process of measuring on this ruler has similar steps as that of other scales. However, to make the procedure clearer and more understandable, here are the steps to measure on this ruler.
- Fix 0 at the starting point.
- Hold the ruler and align it parallel to the object.
- Check the last count on the ruler that meets the end of the object’s dimension.
- Calculate the final result by noting the inches and smaller units.
These steps need kind attention to eradicate the possibility of the minutest measurement mistake.
Continuing in the sequence, the fractional rulers are also a type that scales the length but shows the measurements in fractions.
They show the markings in the fraction form, such as ½, ⅜ on ruler.
Let’s take a glance at it.
How to Read a Fractional Ruler?
A fractional ruler is a variety of scales that are mostly based on inches and their fractions. It is more difficult to use and take measurements and hence poses higher chances of observational errors.
The measurement division in a fractional scale has proportional breakups as follows:
1 Inch ⇾ Half inch (1/2) ⇾ Quarter inch (1/4) ⇾ ⅛ inch ⇾ 1/16 Inch ⇾ 1/32 Inch
For example, reading ⅛ inch on a ruler will be much easier to convey than providing the 0.125 inch (0.32 cm) value.
The basic purpose of using it is to simplify the conversion of basic units into fractional measurements.
Errors in Reading a Ruler
The errors in calculations have been ingrained in several human activities, which are reflected in some popular incidents. Some examples of it are Columbus’s miscalculation that took him to the US instead of Asia and the Disneyland roller coaster derailment in Tokyo in 2003 caused by using 44.14 mm axles instead of 45 mm ones.
Similarly, while measuring a ruler, some basic errors may also occur, especially when impromptu efforts are applied. To overcome these mistakes, we must first understand them. Some basic measurement errors while reading a ruler are discussed below.
- Parallax Error: It occurs when the observer is not adequately concentrating on the measurements of the rulers due to differences in angle of view. This can lead to an increase or decrease in the final measurement result.
- Zero Error: This error occurs when the zero mark is not exactly at the starting point. Such non-alignment can amplify or contract the final measurements, which can eventually inflate the mistake in the final values.
- Ruler Positioning Error: As the term signifies, it can occur due to the incorrect positioning of the ruler or the object. This happens when the object has an irregular edge or has tilt or similar dispositioning.
These can lead to miscalculations in the measurements and misleading observations in the final results. To learn how to read a ruler accurately, these errors must be checked and addressed.
Uses of Reading a Ruler
Being the elementary step in a major physical process, the rudimentary practice of reading a ruler finds several uses in different domains. Some of its notable applications are mentioned as follows:
- Measure the Length: The fundamental use of reading a ruler is to measure the length or dimensions of objects. This can be further used to calculate its area, volume, or other geometric values.
- Convert the Measurements: The famous Great Kersten Blunder has its root cause in basic measurement conversion error that caused the loss of Vigor, a spacecraft to study Venus. Understanding the basic value conversion between the measurement standards is essential, even while using a ruler, to get precise measures in respective SI units.
- Used for Various Purposes: Taking measurements is an integral part of some basic activities such as engineering tasks, carpentry works, construction, and even art and drawing.
The above-mentioned uses show how basic measurement-taking can be utilized in simple or sophisticated fields. As the limits of human desires and inquisitiveness are stretching to new heights, being accurate in scaling has become a sin qua non.
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Conclusion
Taking a measurement is the base of a greater chunk of mathematics, ranging from drawing rays and lines to studying advanced Euclidean geometry. But a ruler is the most fundamental tool, to begin with, to understand taking accurate measures. Hence, it makes it extremely important to learn how to read a ruler, especially for students in their initial stages of academic years to introduce mathematical thinking.
Subsequently, eradicating the errors in the process also demands attention. Hence, the above discussion is of higher importance in reading different types of rulers.
FAQs
Ans: Metric and imperial units are the two major systems to take measurements. In a ruler,
the metric scale measures length in cm and mm, while the imperial unit takes inches as the standard unit.
Ans: The error occurs due to incorrect observation of the measuring scale or the object
primarily due to
differences in the angle of view.
Ans: Reading a ruler has immense use in engineering works, construction activities,
carpentry, and in the education field.
Ans: The regular size of a ruler stands at 15 cm. However, scales of longer lengths are also
available based on their use in the respective fields.
Ans: The formula to convert centimeters to inches is by multiplying the cm value with 0.3937,
i.e. cm x 0.3937 = inches. To convert inches to centimeters, multiply the inches by 2.54, i.e., inches X 2.54
= cm.
