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VOOZH | about |
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VOOZH | about |
Unit of Power is Watt (J/s). It is named after the scientist James Watt in recognition of his contributions towards developing the steam engine. Power is defined as the rate at which work is done. Hence, the base unit of power is the unit of work divided by the unit of time. Several units used to measure the magnitude of power include Watt, Horsepower (HP), erg/s, BTU/hr etc.
In this article, we will learn the definition of Power, its unit in various systems, conversion between them, some practice problems and frequently asked questions related to the unit of power.
Power is a physical quantity that is a measure of energy transfer rate. Therefore, power is defined as follows,
Power is the rate of work done or the rate at which energy is transferred from one system to another.
In physics, Power is denoted by the symbol P.
Power is calculated using the following formula:
P = W/t
where,
P = Power gain or loss.
W = Work done, and
t = Time taken
Unit of Power is a measure of the rate of work done or the rate at which energy is transferred from one system to the another. It represents the unit work done in unit amount of time.
The formula for power is Work done divided by the time taken. Thus, unit of power would directly depend upon the unit of the work done and the unit of time.
The SI unit of Work is Joule (J) and that of time is second (s). Thus, SI unit of Power would be J/s. It is called as Watt (W) in recognition to the name of the scientist James Watt.
Hence, SI unit of Power is Watt. Other units of power are horse power, ergs/s, BTU/hr, etc.
The dimensional formula for power is [M1L2 T-3]. It can be derived using the formula for power, i.e. Power = Work Done / Time Taken
Substituting the dimensions for work and time, we get,
Dimension of Power = [M1L2T-2] / [M0L0T1]
Dimension of Power = [M1L2T-3]
1 Watt is basically the SI unit of Power, i.e 1 J/s. It represents the power in which 1 Joule of work is done in 1 second of time.
S.I. unit of power is joules per second abbreviated as J/s and also called as Watt (W). It can be derived as follows:
We know that Power = Work / Time
Hence, SI unit of Power = SI unit of Work / SI unit of Time = Joule/second = J/s = Watt (W).
SI Unit of Power is Watt (W).
Unit is a standard measurement of any physical quantity that is used to express the size or magnitude of any physical quantity. There are different units chosen for the measurement of same physical quantity for its convenient representation in terms of magnitude. The unit of power in different systems is mentioned below:
System | Unit |
|---|---|
MKS system | Watt (J/s) |
CGS system | erg/s |
Imperial system | BTU/hr |
Others | cal/s, Horsepower |
Similar to other SI units, the value of Watt can be adjusted to different magnitudes as shown in the table below:
Unit of Power | Symbol | Equivalent in Watt (W) |
|---|---|---|
Watt | W | 1 |
Milliwatt | mW | 10-3 |
Microwatt | μW | 10-6 |
Nanowatt | nW | 10-9 |
Kilowatt | kW | 103 |
Megawatt | MW | 106 |
Gigawatt | GW | 109 |
Conversion factors for different units are given in form of a table as follows. These conversion factors can be used to convert any unit of power to its corresponding another unit.
From/To | Watt | Erg/s | Horsepower | Kilowatt | Megawatt | Gigawatt | BTU/hr | Cal/s |
|---|---|---|---|---|---|---|---|---|
Watt | 1 | 107 | 0.00134 | 10-3 | 10-6 | 10-9 | 3.412 | 0.239 |
Erg/s | 10-7 | 1 | 1.34 x 10-10 | 10-10 | 10-13 | 10-16 | 3.412 x 10-7 | 2.39 x 10-8 |
Horsepower | 746 | 7460000000 | 1 | 0.746 | 0.000746 | 0.000000746 | 2536.4 | 177.62 |
Kilowatt | 103 | 1010 | 1.34 | 1 | 0.001 | 0.000001 | 3400 | 238.1 |
Megawatt | 106 | 1013 | 1340 | 1000 | 1 | 0.001 | 3400000 | 238095 |
Gigawatt | 109 | 1016 | 1340000 | 1000000 | 1000 | 1 | 3400000000 | 238095000 |
BTU/hr | 0.293 | 2.931 x 106 | 0.000394 | 2.941 x 10-4 | 2.941 x 10-7 | 2.941 x 10-10 | 1 | 0.0700 |
Cal/s | 4.2 | 42000000 | 0.0056 | 0.0042 | 0.0000042 | 0.00000042 | 14.28 | 1 |
Read More,
Problem 1: Convert 2500 Watts to Kilowatts.
Solution:
We know that, 1 kW = 1000 W
or, 1 W = 0.001 kW
Thus, 2500 W = 2500 x 0.001 kW
⇒ 2500 W = 2.5 kW
Thus, we get 2500 W equal to 2.5 kW.
Problem 2: Convert 3.5 Kilowatts into SI unit of Power.
Solution:
We know that, SI unit of Power is Watt.
Also, 1 kW = 1000 W
⇒ 3.5 kW = 3.5 x 1000 W
⇒ 3.5 kW = 3500 W
Therefore, we get 3.5 kW equal to 3500 W.
Problem 1: Convert 4200 Watts to Cal/s.
Problem 2: Convert 220 Kilowatts to Megawatts.
Problem 3: Convert 4 Horsepower to Watts.
Problem 4: Convert 2.5 Kilowatts to Horsepower.
Problem 5: Convert 8 Megawatts to BTU/hr.
