What is a Ruler?
A ruler is a device or tool for measuring the length of objects and drawing straight lines. The ruler is helpful in measuring the length in both metric and customary units. Usually, rulers come with standard markings at fixed intervals either in centimeters marked on one side and inches on the other. The markings forming the intervals on the ruler are known as hash marks. The numbers denoting the length measures are written below the longer hash marks.
The image represents a ruler with a centimeter scale on one side and an inch scale on the other. The numbers are marked under the longer hash marks, 0 to 25 for cm and 0 to 10 for inches.
What are the Different Kinds of Rulers?
There are different kinds of rulers based on the material they are made of. Rulers come in different materials such as wood, plastic and metal. The different types of rulers are wooden rulers, steel rulers, plastic rulers, folding rulers, metal tapes and plastic tapes.
How do we Read a Ruler?
A ruler can be read either from its centimeter scale, milliliter scale or the inches scale.
The smaller hash marks on the centimeter scale side denote measurement in millimeters as they are smaller than centimeters. Ten millimeter hash marks form 1 centimeter.
The inches are denoted by the long hash marks on the opposite side of the centimeter scale of the ruler as inches are larger in value than centimeters.
How do we Measure Length Using a Ruler?
To measure the length of any object or line using a ruler, place the ruler along the length to be measured such that one end of length is placed over the zero mark of the ruler. The mark on the ruler coinciding with the other end of the length determines the measure of the length of an object or line.
You can select the ruler scale depending on the requirements or your choice. However, as a usual practice centimeters or millimeters are used for smaller objects and inches or feet are used for larger objects.
Solved Examples
Example 1: Find the measurement of the following bar in centimeters.
Solution:
The bar starts at the hash mark, 0 of the ruler while the other end of the bar is on the hash mark, 9.
Hence, the bar measures 9 centimeters.
Example 2: Alice is trying to measure the length of a pencil. She uses a ruler to measure it. Can you find the length of the pencil?
Solution:
As you can see, the tip of the pencil coincides with 0 and the base of the pencil is at 11.
Hence, Alice’s pencil measures 11 centimeters.
Example 3: Find the reading of the following bar on the ruler in inches.
Solution:
As you can see, the bar begins at 11 and ends at 13 on the inch scale of the ruler. Now, if we subtract 11 from 13, we will get 2 inches, which is the length of the given bar.
So, the length of the bar is 2 inches.
Rulers are not only used for drawing straight lines but used for measuring objects, in carpentry, engineering and measuring the length of roads.
There are four units of measurement in a ruler, millimeter, centimeter, inch and feet. Measuring tapes also provide measurements in meters.
There are 30 centimeters in a standard ruler.