Power (P) is the rate of doing work (W), so its fundamental formula is:
P=W/t
That is:
Power = Work divided by time.
Clear explanation: Power is equal to:
How much work is done (in joules) divided by the time (in seconds) it took to do that work.
For example:
Problem: If a construction worker pushes the wheelbarrow, expending 50 J of work in 2s, how much power does he use?
Answer: 50 J divided by 2 s is 25 W so, the power is equal to 25 watts.
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For electrical engineering and electronics, power is calculated as:
P = I2R, or
P= V2/R, or
P= VI
where P is power, I is current, R is resistance, and V is voltage.
The big power formulas are:
Formula 1 - Electrical (electric) power equation:
Power P = I × V = R × I2 = V2 ⁄ R
where power P is in watts, voltage V is in volts and current I is in amperes (DC).
If there is AC, look also at the power factor PF = cos φ and φ = power factor angle (phase angle) between voltage and amperage.
Formula 2 - Mechanical (mechanic) power equation:
Power P = E ⁄ t = W
where power P is in watts, energy E is in joules, and time t is in seconds. 1 W = 1 J/s
There is much potential for confusion between the value for Work (measured in joules but often written in formulas as W) and Power (measured in watts and often written in formulas as W). However, symbols for quantities (work) are italicised, W,whereas symbols for units are upright.
In these formulas, W always refers to watts, although units should never be written in equations.
Scroll down to related links and look at "Calculation: electrical voltage, current, resistance, and power". Look at the written italic letters and normal letters. The SI unit of "work or energy" is the same. One joule is the amount of work done when an applied force of 1 newton moves through a distance of 1 metre in the direction of the force. That is energy.
Not enough information. Power = current x voltage. Since voltage can be anything, there is no way to calculate power. Time is irrelevant; though once you have the power, it can help you calculate energy (energy = power x time).
output power/Rated power
If a load takes 50 kW at a power factor of 0.5 lagging calculate the apparent power and reactive power Answer: Apparent power = Active power / Power Factor In this case, Active power = 50 kW and power factor = 0.5 So Apparent power = 50/0.5 = 100 KVA
formula are given at www.calculatoredge.com
The length of the cable is determined by the distance from the center of the distribution panel to the center of the load.
How do you calculate 3ph AC motor power?
To be able to calculate a mi to the second power you need to
You can't "calculate" it...
If you know the power you do not need to calculate it by anything. And if you don't, the answer will depend on what measure you do know!
If you have 3 to the power 2 to the power 2, without any parentheses, you have to calculate from right to left. In this case, calculate 2 to the power 2; then calculate 3 to the power (whatever the result you get). If there are parentheses, do the calculation in parentheses first.
This calculation will give you the ratio, in decibels, between two power values. For example, you can calculate the difference in dB between two amplifiers with different power output specifications calculate in dB Power Ratio.
Usually there is not.
Not enough information. Power = current x voltage. Since voltage can be anything, there is no way to calculate power. Time is irrelevant; though once you have the power, it can help you calculate energy (energy = power x time).
17W
magic
Power = Work/Time Time = Work/Power Work = Power * Time See related links for a power calculator. Insert work and time to calculate power.
the objective lens has the power of that lens inscribed on it