TOPIC 1.2 BASE QUANTITY VS VECTOR QUANTITY

"How far is it from here?"

"What is the time now?"

"How heavy is it?"

The above conversations are familiar in our life. Yes, we always tend to know how much or how many, in other words, quantity.

Physical quantity is the quantity that can be measured. For example, height, distance, time, etc. Can you name other examples of physical quantity?

At the end of subtopic, you are able to:

- explain what base quantities and derived quantities are.

- list base quantities and their units.

- list some derived quantities and their units.

- express quantities using prefixes.

- express quantities using scientific notation.

- express derived quantities as well as their units in terms of base quantities and base units.

- solve problems involving conversion of units.

We need a systematic way to measure and record, or we call "Standard". Without this "Standard", we will always argue about the measurement. For example, in ancient times, we use feet for measuring length. However, everyone's foot is different in size. So, how do we solve the problem?

Indeed, we need a system to standardize the method of measuring. We call this SI unit (Le Système International d'Unités).

For example, we use metre as SI unit for measuring length. Everyone in this world knows metre and uses metre. This is a standard that can be accepted by everyone.

There are two types of physical quantity.

a) Base quantity

b) Derived quantity

How to remember?

Extra -> Electric current

Learning -> Length

To -> Time

The -> Temperature

Max -> Mass

There are a lot more of derived quantities. Can you name other physical quantities that are derived quantities?

Look at the picture above. Who is wrong with his statement?

Actually both are not wrong. Although they have different values, or we call it magnitude, the unit used is different.

In life, we will not say the distance between KL to JB is 300,000 meter. This is difficult to say it out. Or we will not say the storage of pendrive is 1000,000,000 bytes. In order to make our communication or writing easier, we use prefix or scientific notations.