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Ikaros Spacecraft Successfully Propelled In Space
An anonymous reader writes "Japan's IKAROS spacecraft has already successfully deployed the first solar sail in space, but today it made the only first that really matters: it successfully captured the sun's rays with its 3,000-square-foot sail and used the energy to speed its way through space. Each photon of light exerts 0.0002 pounds of pressure on the 3,000-square-foot sail, and the steady stream of solar exposure has succeeded in propelling the nearly 700-pound drone."
As we all know that I Ikaros (engl. Icarus) flew too close to the sun. This is a bad name for a space craft or any other flying device to call it after an pilot who messed up.
...giant fighting robots with swords will be propelled by solar sails throughout the solar system!
What exactly is wrong with Watts per Day ?
Your electricity bill is reported in Kilowatt Hours ... but most people don't want to know how many thousand Watts their fridge uses in an hour, a day is a more human-relatable quantity, especially as hours per day is one of those silly "Imperial" measurements that anyone under 35 cannot manage to convert without getting a migraine. Also, it gives a meaningful idea of the consumption between recharges as most people will recharge their devices at the end of the day / overnight.
When it comes to portable devices where the consumption is miniscule (compared to a fridge), Watts per Days seems like a good choice for people to get their head around.
Still, just for your benefit ...
Watts per Day * 0.00004167 will give you your coveted Kilowatt Hours. Enjoy.
Watts per day is a measure of power increase.
Any increase / decrease is still measured in the same units as the base quantity. So your statement is meaningless ... is a negative value of "watts per day" STILL a measure of power INCREASE ???
41.66W * 24 hours = 1000Wh
Facepalm ... A WattHour is already the amount of Watts consumed in ONE hour ... it's a rate of consumption. By your logic :-
A fridge using 41.66W * 24 hours uses 1000Wh.
A light bulb using 10W * 168 hours uses 1680Wh.
Holy shit, that light bulb uses more electricity than the fridge ... of course it's used more electricity, but over a completely different time period ... your comparing apples and oranges.
Both Watts per Day and Kilowatt Hours are both rates of consumption as they involve power (in watts) divided by a time period (usually to compare the relative consumption of two appliances).
The only issue is the (confusing) use of "per" ...
KWh (KiloWattHours) and Wd (WattDays) can be converted back and forth using the above stated 0.00004167 (essentially 1/24000) conversion factor.