Learn more physics!
Explains the difference between 2400 W and 3kWh
- Cori Barrera (age 15)
Watts are a unit of power, and kilowatt-hours are a unit of energy.
Power is a measure of energy per unit time, and a watt measures how
many joules (the standard international unit of energy) of work can be
done in one second. A kilowatt-hour is the amount of energy
corresponding to the work that can be done with a one kilowatt (one
thousand watt) source of power operating for one hour (which is equal
to 3.6 million joules). The reason for the different units of energy is
that a kilowatt-hour is much larger than a joule and is more convenient
in some situations. Hope this helps!
(republished on 07/13/06)
Follow-Up #1: 50,000 Watts and 50 kwh
How many watts in 50 kwh?
Is 50,000 watts the correct answer?
- Al Bowers (age 36)
Eden Prairie, MN, USA
There are two conversions going on here. One is that the letter k in kwh stands for kilo or 1,000. So there are 50,000 wh in one kwh. The other is that the h in kwh stands for hour. A Watt is a rate of using energy. A Watt-hour is an amount of energy. You pay the electric company for the amount of kwh you use.
(published on 08/03/08)
Follow-Up #2: windmill power
Okay, So I am looking at buying a windmill that produces 500 KWH per month at a rate of 12 mph. How many watts does that come out to be per month?
- Steven Clark (age 20)
Actually, you already know how much energy your windmill produces per month (under these conditions): 500kWh. Watts (and kilowatts) are units of power
, energy per time. When you multiply by a time (say one hour) you get units of energy
, such as kWh.
What you can figure out is how much power you typically get, in Watts. If you get 500 kWh/month that's 500kWh/(24*30 h/month). (I'm using 30 day months.) That's 500/720 kW, or about 0.7 kW= 700W.
(published on 04/01/10)
Follow-up on this answer.