Question

In ancient times people used which of the following to measure length?
A) Wooden scale
B) Meter tape
C) Hand span.
D) All of the above.

Answer 1

Hint: Meter is the standard unit of measurements but sometimes other units of lengths like centimeters, millimeters, and kilometers are also used for the sake of convenience. The type of units used depends on the magnitude of the length to be measured.

Complete step by step answer:
Measurement is a process of including an object with a standard unit of measurement, Standard unit of measuring length is called meter. We can use a variety of objects as units of measurement of length.
We can measure the length of an object by using ‘hand span’, ‘forearm length’, or ‘footstep’ as the units of measuring length. But hand span, forearm length and footstep cannot be used as a standard unit’s measurements because their length is not the same for all the persons. The length of the hand-span, forearm-length, and footstep of different people is different. It varies from person to person. So, hand span, forearm length, and footstep are not the standard units of measuring lengths.
But in ancient times, people were using a hand span to measure the length.
A unit of measurement which has a fixed value that does not change from person to person or place to place is called a standard unit of measurement of length. If a meter is used by one person or another person, whether the meter is used in one country or another country, it always represents exactly the same length. The length of the meter does not change from one person to another person or place to place. It is compulsory to have standard units of measurements for the sake of uniformity in measurements.
Wooden scale, meter tape both are not used in ancient times. It is a standard instrument of measurement of length.

Thus, the correct option is (C).

Note:
SI unit is defined as the standard reference of the physical quantity which is used to compare given physical quantity.
There are three systems of units.
(i) F.P.S ( Foot-pound-second) system
(ii) C.G.S (Centimeter-gram- second) system
(iii) M.K.S (Meter-kilogram-second) system.