Introduction to Power

The definition of power in physics is considered as the time rate of doing the work or delivering the energy. It is expressible as the amount of work done W, or the transferred amount of energy, i.e. W/t, divided by the time interval ‘t’. An available amount of work can be completed by a motor with low power in more time or by a motor with high power in less time. The unit of power is the same as the unit of energy, i.e., work per unit time, such as foot-pounds/minute, joules/second, and ergs/second. In addition, the power is also expressible in the form of the product of the speed of the object and the force applied on the object for making it move in the direction of the force. 

Power Formula

Power is the rate at which work is done on the object. It is a quantity based on time, which is related to what time a job is done. The formula for finding out the power is as follows:

Power = Work/time i.e. P = W/t

Units

Power’s dimension is the amount of energy divided by the time taken. Moreover, the SI unit of power is watt ‘W’ in the international system, and watt is equal to 1 joule per second. Some other general measures of power are horsepower (hp), where 1 hp = 745 watts approximately, ergs per second ‘erg/s’, foot-pounds/minute, dBm, etc.

Average Power

Just have a look at this simplified example that says; burning 1 kg of coal produces more energy as compared to detonating 1 kg of TNT(Trinitrotoluene). However, the TNT reaction produces energy more rapidly and delivers much more power as compared to coal.

Electrical Power Formula

You can use the power factor formula in the electrical circuits so that you can calculate the power with the assistance of the following formulas given below:

1st Electrical Power Formula, P = V × I

2nd Electrical Power Formula, P = I2R

Combing both, you will get: P = V2/R

The formulas given above have:

‘V’ = Voltage across two terminals

‘I’ = Electric current 

‘R’ = Resistance

The power factor formula can be used for calculating the power in a circuit (with the help of active voltage as well as current within a certain period of time). However, ‘Watt’ is considered as the standard metric unit for power.

Determining the Power Calculation Formula

For calculating the formula of power calculation, we have to keep in mind three equations that form the power triangle:

P (watts) = V (volts) x I (amps)

P (watts) = I2 (amps) x R (Ω)

P (watts) = V2 (volts) /R (Ω)

Power Consumption Formula

Before calculating the formula of power consumption, you have to look at what amount of watts the device uses in a single day. You can find it easily by multiplying the watts mentioned on the box with the hours of usage in a single day.

Power Consumption Formula = Watts * Hours Used/Day

The result that you will be able to see is ‘watt-hours’, which will be considered as the power consumption in a single day by that device.

Mechanical Power

In mechanical systems, power is considered as the forces and the movement. Particularly, power is the product of the velocity of the object and the force on that object or the product of a shaft’s angular velocity and torque on the shaft. Moreover, mechanical power is also defined as the work’s time derivative.

Mechanical Advantage

When a mechanical system has zero losses, then the power used in the input of the system should be equal to the output power of the system. This gives us the simple formula for the system’s mechanical advantage.

Wind Power

Wind power is a form of energy conversion where the turbines convert the wind’s kinetic energy into electrical or mechanical energy, which can be utilized to generate power. The power produced from the wind is said to be a renewable source of energy. Historically, wind energy was used for various tasks like pumping water, grinding grain, etc.

Conclusion

This study material for power in physics concludes that power is the time rate at which any work is completed successfully. In addition, it is a measure of how fast the energy can be exerted. The ‘work’ is related to the ‘power’, and the power can be found using the work by considering the amount of time applied.