Physics is the study of nature and natural phenomena and is considered the base of all science subjects. It is based on experimental observations, and its theories use many physical quantities that have to be measured. Measurement is the base of all scientific studies and experimentations: it is the process of finding an unknown physical quantity by using a standard quantity. This chapter covers systems of units, the SI base quantities, plane and solid angles, clocks, accuracy and precision, approximation and rounding off.
1. What Is Measurement?
We need three things for a perfect measurement:
- an instrument
- a standard quantity
- an acceptable unit
Example: if the length of a book is 30 cm, then length is the physical quantity, the ruler is the instrument, 30 is the magnitude and 'cm' is the unit. This process is called measurement.