Question

Unit of energy in SI system is?

Answer 1

Hint: Energy and work are two sides of the same coin so both are more or less same that’s why both of them have the same units. So, now what we can do in this question is find out the unit of work in the standard system which will give us the unit of energy in the SI system.

Complete step-by-step solution:
Let us first discuss what energy is?
Energy is defined as the capacity of doing work. So, we can say energy is measured with the same unit as that of work.
There are different forms of energy mainly-
Kinetic energy- it is the energy possessed by a body in motion
Potential energy- it is energy possessed by a body as a result of its position.
Now, we will discuss what the SI system of units?
It is also called the international system of units. There are only seven basic units of quantities and their other units are derived units from these seven units only.
Now, we will find out the SI unit of energy,
It is Joule, named after English physicist James Prescott Joule. He discovered the relationship between heat and mechanical work, that helped in discovery of law of thermodynamics.
Joule is also in the MKS unit that is meter, kilogram and second unit.
1 Joule is equal to the work done by a force of one newton to move an object one meter.
We also have a CGS unit that is centimeter, gram and second unit and the unit is erg.
1 erg is equal to \[{{10}^{-7}}\]Joule. It is defined as work done by the force of 1 dyne to move it 1 centimetre.
Other units in which energy can be measured is-
Horsepower, kilowatt-hour, calorie, etc.
Kilowatt hour is the commercial unit of energy. It is the larger unit of measurement because the SI unit becomes small for larger quantities.

Note: There are only seven base units in SI system (length, mass, time, electric current, temperature, amount of substance, luminous intensity )and the other ones are the derived units also the SI unit of energy and work are same so don’t get confused between the two as energy is defined as the capacity to do work.