Fundamental Units: Such units which cannot be derived from other units are called fundamental units. For example, length, mass, temperature, electric current and light intensity etc.
Derived Units: The units which are derived from the fundamental units are called derived units. For example, force, acceleration, velocity, volume, pressure, area etc.
What is meant by Measurement?
MEASUREMENT: The following information about a body or an event is called Measurement. ● The size and nature of a body are described with a scale. ● A clock describes an event. ● Hence the reading will give the scale or clock about a body or an event is known as Measurement.
What is the importance of measurement?
IMPORTANCE OF MEASUREMENT: ● In our daily life, we get knowledge of things through our five senses, touch, smell, taste, sight and hearing. However, our senses often do not provide us with correct information. ● We use measuring devices generally called apparatus to get the correct measurement. Such as: ● To measure volume we use a measuring cylinder. ● For mass, we use a common balance. ● For the measurement of length, a meter scale is used. ● A vernier calliper can measure correctly up to 0.1 mm and a micrometre screw gauge can measure correctly up to 0.1 mm. ● Any instrument whose calibration is in doubt must be checked or discarded
Define physical quantities?
PHYSICAL QUANTITIES: Every material has certain characteristics. These are to be measured to specify them. For instance, if we want to specify the characteristics ofbrick we will have to measure its length, width, height and mass. Such characteristics are called physical quantities.