Question

1. What is a unit? Write down the units of mass, temperature, power, and density.

2. Write any three differences between fundamental units and derived units.
3. What is the SI system? Why has the SI system been developed? Give reasons.
4. What is the unit of pressure? Why is it called a derived unit? Give reasons.

Answer 1

A unit is a standard quantity used to express a physical measurement. The units of mass, temperature, power, and density are kilograms (kg), degrees Celsius (°C), watts (W), and kilograms per cubic meter (kg/m³), respectively. Three differences between fundamental units and derived units are their definition, usage, and conversion. The SI system is a globally recognized system of measurement developed to promote consistency, accuracy, and ease of communication. The unit of pressure is called Pascal (Pa) and is a derived unit.

Step-by-step explanation:

A unit is a standard quantity used to express a physical measurement. In the metric system, different units are used for different physical quantities. The units of mass, temperature, power, and density are kilograms (kg), degrees Celsius (°C), watts (W), and kilograms per cubic meter (kg/m³), respectively.

Three differences between fundamental units and derived units are:

1. Definition: Fundamental units are independent and cannot be defined in terms of other units, while derived units are defined as mathematical combinations of fundamental units.
2. Usage: Fundamental units are used to measure basic physical quantities, while derived units are used to measure derived quantities.
3. Conversion: Fundamental units are used as a basis for converting between different units, while derived units are used indirectly in conversions through equations and formulas.

The SI system, or the International System of Units, is a globally recognized system of measurement. It was developed to provide a uniform and standardized system for measurements. The SI system has been developed to promote consistency, accuracy, and ease of communication in scientific and everyday measurements. The primary reasons for developing the SI system are to facilitate international cooperation, improve precision, and enhance the reliability of measurements.

The unit of pressure is called the Pascal (Pa), which is a derived unit. It is named after Blaise Pascal, a French mathematician and physicist. Pressure is defined as force per unit area, and since force (Newton) and area (square meter) are both derived units, the unit of pressure is also a derived unit.