Physical Quantities

In our daily life, we measure many things, like the weight of fruits, the temperature of the body, or the speed of vehicles. These measurements, such as mass, weight, distance, speed, temperature, and volume, are called physical quantities. Every physical quantity has two parts: a value and a unit. For example, if Swarali walks two kilometres every day, "two" is the value and "kilometres" is the unit of distance.

1. Fundamental Quantities: These are basic quantities like length, mass, and time. They are not derived from any other quantities.

2. Derived Quantities: These quantities are formed from fundamental quantities. For example, speed is derived from distance and time (speed = distance ÷ time).

3. Scalar Quantities: A scalar quantity can be described completely with just a value and a unit without any direction.

Examples include:

• Length (e.g., 2 meters)
• Temperature (e.g., 37°C)
• Mass (e.g., 50 kilograms) These quantities don't need direction to be understood.

4. Vector Quantities: A vector quantity is one that requires both a value and a direction to be completely described.

Examples include:

• Displacement (e.g., 20 kilometers north)
• Velocity (e.g., 500 km/h towards Mumbai): These quantities need both magnitude and direction to be meaningful.