# What is power?

Power is a physical quantity equal to,as a rule, the rate of change in the energy of the whole system. Speaking more specifically about what power is equal to, we can say that it directly depends on the ratio of the work performed for a certain period of time and the size of this very period of time. There is the concept of average and instantaneous power. That is, if we are talking about the power of the system in a certain period of time, then this is the average power. If the power is considered at the moment, then it is instantaneous power. Hence we obtain the following formula:

N (power) = E (energy) / t (time)

Consequently, the integral obtained from the instantaneous power indicators for a separate time period is equal to the total volume of energy used during a given time period.

As a unit of measurement for a given valueit is customary to use a watt. Taking into account the previous formula, we can say that 1 Watt = 1 J / 1 s. Horsepower is another popular unit for measuring power.

## What is the power in mechanics?

The force acting on the body inmovement, doing the work. In this case, the power is determined by the scalar product of the force vector and the velocity vector with which the system moves in space. I.e:

N = F * v = F * v * cos a

In this formula, F is the force, v is the velocity, a is the angle connecting the velocity vector and the force vector.

If we are talking about the rotational motion of the body, then the following formula is appropriate:

N = M * w = (2P * M * n) / 60

In this formula, M is the moment of force, w is the angular velocity, P is the Pi number, and n is the number of revolutions per given time unit (per minute).

## What determines the power of electrical energy?

The term electrical power characterizesrate of change or transmission of electrical energy. Studying the AC network, in addition to the concept of "instantaneous power", which corresponds to the traditionally physical definition, it is customary to use active power. Active power is equal to the average instantaneous power for a period of time, an indicator that determines the reactive power corresponding to the energy moving between the source and the consumer without dissipation and the total power value, which is determined by the product of the active current and voltage value, without taking into account the phase shift.