Introduction
The goal of physics is to provide an understanding of nature. The science of physics was developed to explain our physical environment.
Estimation by orders of Magnitude of size (Length, Area and Volume) Mass, Time
In no subject does measurement play as important a role as in science. Real science cannot exist without measurement. According to Lord Kelvin, one of the greatest scientists, unless you can measure what you are speaking about and express it in numbers you have not started 'Exact Science'.
Measurements
Everything that we use in our daily life is ultimately governed by principles of physics. All gadgets we use everyday at home, bicycles and cars, all different types of machinery and instruments, work on principles of physics. Hence to understand even the elementary working of these things, the study of physics is essential.
International System of Units
In 1960, the Eleventh General Conference of Weights and Measures recommended an International System of Units (abbreviated as SI) based on the metric system of measurement. When the recommendation was accepted in 1968, it marked the first time in world history that a single system of units had been established internationally. This helped scientists working in different parts of the world to compare their data (measurements) easily.
Accuracy in Measuring
It is the smallest reading that can be accurately measured while using an instrument or a device.
Significant Figures
These express the degree of accuracy of measurements. It is a statement which gives number of digits up to which we are sure about their accuracy.
Accurate Measurement
Random errors occur in all measurements. They arise when observers estimate the last figure of the reading on an instrument. These include the noise in the room or the mechanical vibrations in the room. These are called random, because they cannot be predicted. The best way of minimizing the error is to take the average of many readings.
Measurement of Length
Different types of lengths are measured by using different types of instruments. Lengths like the length of cloth or length of a line can be measured by using measuring tape, a metre scale or a foot rule.
Vernier Callipers
The meter scale enables us to measure the length to the nearest millimeter only. Engineers and scientists need to measure much smaller distances accurately. For this a special type of scale called Vernier scale is used.
Micrometer Screw-Gauge
Micrometer screw-gauge is another instrument used for measuring accurately the diameter of a thin wire or the thickness of a sheet of metal.
Mass
Mass is the quantity of matter in the body. Mass is measured by finding out the force needed to change the way the object moves. The greater the force needed, greater the mass of the object.
Measurement of Volume
The space occupied by a substance is called its volume. SI unit of volume is cubic meter (m3). The solids whose volume can be calculated by measuring length, width, height, diameter etc. are called regular solids.
Measurement of Time
Thus just as length has units like kilometer, meter, centimeter, millimeter etc., time also has units like year, month, day, hour etc. You must have been hearing quite a lot about the ending of the millennium and starting of the third millennium in the year 2001.
Simple Pendulum
A simple pendulum consists of a heavy or point mass suspended by an inextensible or non-elastic thread from a fixed point.
Summary
International System of (SI) unit has been adopted for measurement by scientists all over the world.
