Students, here we discuss about types of physical quantities. In this chapter as we are going to talk mainly about units and dimensions which are characteristics related to physical quantity measurements. So here we first need to understand what are the types in which the physical quantities are classified.
So you need to understand first that all physical quantities in nature are divided in two categories. first one is fundamental quantities and the second is derived quantities. So let's discuss both of these one by one. If we talk about fundamental quantities, here about fundamental quantities we can say these are physical quantities which are independent of each other and these cannot be further resolved into other quantities. about fundamental quantities we will further discuss in detail.
here you can say, there are seven fundamental quantities. defined as or which are you can say first one is length, second is mass third is time, fourth is current fifth is temperature Sixth is intensity of light. And seventh is amount of substance. About these standard fundamental quantities we will discuss. We will continue our discussion after this slide.
So these are the seven fundamental quantities considered. Which can not be further resolved or dependent upon any other physical quantities. And these are independent from any other physical quantity.
and if we talk about derived quantities, then about derived quantities here we can say, these are physical quantities, which depend on fundamental quantities. Like if we talk about an example, if we talk about speed, you know about speed, it is given as length or distance upon time. So if we talk about the fundamental quantity, the distance is associated with the fundamental quantity length, time itself is a fundamental quantity.
So here speed is dependent upon two fundamental quantities. So to measure speed, directly or indirectly you need to measure distance travelled or the length and the time consumed and combining these by taking the ratio of these two will be able to measure speed. Similarly, force can be given as mass multiplied by acceleration. Acceleration is again dependent upon distance and time. So, one or more fundamental quantities can be clubbed in different relations to obtain the.
Derived quantities will discuss about this There are these derived quantities and fundamental quantities in upcoming slides in more detail