science:why is the units of power called derived?
Your school subject is some kind of science.
Power is not one of the basic seven SI units. Anything not one of the original seven can be obtained in terms of one or more of the seven basic units. Those are called "derived units".
For example Joules is Force*distance
= mass * acceleration * distance
kg m/s^2 * m = kg m^2/s^2
The units of power are called derived because they are derived from the fundamental units of other physical quantities. In the International System of Units (SI), power is defined as the rate at which work is done or energy is transferred. It is calculated as the ratio of work or energy to time.
To understand why power units are derived, we need to look at their definition. Work is defined as the product of force and displacement, and energy is defined as the ability to do work. Both work and energy have their own fundamental units in the SI system - joules (J).
Time is another fundamental quantity with its own unit - seconds (s). When we divide the fundamental unit of work or energy (joules) by the fundamental unit of time (seconds), we get the derived unit of power - joules per second, which is also known as a watt (W).
Therefore, the unit of power (watt) is considered derived because it is derived from the fundamental units of work or energy and time.