In this segment of ‘Introduction to motion and measurement of distances’, we will learn about different units of measurement.
Consider three balls kept on a table. A blue ball, a red ball, and a green ball in that particular order.
Blue, red, and green ball on a table
Now, simply by looking at the image, we can say that the blue ball is nearer to the red ball than the green ball.
Hence, the distance between the red and the blue ball is less than the distance between the red and the green ball.
This comparison of the distances was done visually. But let us see how the absence or presence of units makes a difference in the interpretation of the given data.
Unit of Measurement
Case 1: Units mentioned
Now, suppose that the distance between the red and the green balls is 200 cm and the distance between the red and the blue ball is 100 cm.
As 100 cm is less than 200 cm, the distance between the red and the blue ball is less than the distance between the red and the green ball.
Blue, red, and a green ball at different distances
Case 2: No units mentioned
Now consider this statement “The distance between the red and the blue ball is 100, while the distance between the green and the red ball is 200”.
Here, we can’t say that the blue ball is nearer to the red one or the green one. This is because the given statement doesn’t specify the unit of measurement.
The distance between the red and the blue ball can be 100 m and the distance between the green and the red ball can be 200 cm. Since 100m is greater than 200 cm, the green ball would be nearer to the red one.
So even if the number 100 is less than 200, just by changing the units, we can change the value of the distance. Thus, the unit of measurement is very crucial in measuring the distance between objects. Without units, we can’t comment on how near or far away the given object is.