Question

What is the S.I. unit of energy and power?

Answer 1

Definitions

Energy :

1. Energy is defined as the capacity of doing work.
2. Energy can be stored in different forms, such as nuclear energy, kinetic energy, potential energy, etc.
3. Energy can't be created or destroyed, but can be transformed from one type to other.
4. The dimensional formula for energy is $[{\mathrm{M}}^1{\mathrm{L}}^2{\mathrm{T}}^{-2}]$.
5. The mathematical expression for energy is $\mathrm{E}={\mathrm{mc}}^2$, where $\mathrm{E}$ is the energy, $\mathrm{m}$ is the mass of an object, $\mathrm{c}$ is the speed of light.

An illustrative diagram of different forms of energy is given below.

Power :

1. Power is defined as the rate of doing work in the minimum time.
2. Power is the amount of energy converted per unit of time.
3. The dimension of power is $[{\mathrm{M}}^1{\mathrm{L}}^2{\mathrm{T}}^{-3}]$.
4. The mathematical expression for power is $\mathrm{P}=\frac{\mathrm{W}}{\mathrm{t}}$, where $\mathrm{P}$ is the power, $\mathrm{W}$ is the work done , $\mathrm{t}$ is the time.

An illustrative diagram of power is given below.

SI unit

1. Joule is the SI unit of energy.
2. One joule is the energy transferred to an object when a force of one newton acts on that object in the direction of force through a distance of one meter.
3. Watt is the SI unit of power.
4. One watt is defined as one joule of energy used in one second.