Steve Jackson Games Forums Thaumaturgic Automata and Draw Power
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 01-21-2014, 03:20 AM #41 scc   Join Date: Mar 2013 Re: Thaumaturgic Automata and Draw Power Jeff, technically kilowatt's already have a time based component, specifically a single watt is one Joule per second, thus anything measured in watt-seconds would deal in the change in current or whatever. More to the point no STORED source of energy, which is what the 360 kJ = 360 kWs => 1 FP equation is for dealing with, would be measured in kWs, it would be measured in straight kilowatts, and while sources of energy (IE:Generators) would be rated in straight kilowatts they could also be rated in how much they can generate per second
01-21-2014, 09:10 AM   #42
whswhs

Join Date: Jun 2005
Re: Thaumaturgic Automata and Draw Power

Quote:
 Originally Posted by scc Shouldn't those two be the other way around? From the way it stands it looks like if I cast Draw Power on, lets say a flywheel because I don't think batteries can be the target of that spell, that was storing 360 kW I would get 1 FP for every second I maintained the spell, ok, it costs 1 to maintain so I'd need a 720 kW flywheel to have a reason to maintain it, but still. Now if I find a power line that supplies 360kWs, or 360 kW a second I can only draw one point per casting
No. Just no. That's completely contrary to the physics.

A power line does not supply kWs; it supplies kW. kWs is not "kW a second," it's "kW sustained over a time of a second" or "kw times seconds." If it were "kW a second" the notation would be "kW/s." One is multiplying; the other is dividing.

And talking about "kW a second" is nonsense in this context. The kW is not a unit of energy; it's a unit of power. The unit of energy is the kJ (or kWs). A power line that supplies 360 kW is supplying 360 kJ a second; the "a second" is already there, built into the "kW." (That is, 360 kJ/s = 360 kWs/s = 360 kW.)

Bill Stoddard

01-21-2014, 10:55 AM   #43
sir_pudding
Wielder of Smart Pants

Join Date: Aug 2004
Location: Ventura CA
Re: Thaumaturgic Automata and Draw Power

Quote:
 Originally Posted by malloyd I think he's considering calories a non-SI unit and assuming that makes them a US Engineering one. Calories are actually metric too, the system having been defined before determination of the mechanical equivalent of heat.
Yes but calories aren't SI and joules aren't US customary. "Food calories" are kilocalories and food energy is given in joules in SI countries.
Quote:
 Anyway, the most common US Engineering energy unit is probably is the kilowatt-hour, electrical units being the same in both systems,
US engineers and physicists use metric units, at least mostly, when they can.
Quote:
 though horsepower-hours are occasionally met with.
That would also be more consistent with GURPS being US customary.

However it appears I was making a far to subtle joke, my apologies. I know why GURPS does it the way it does. We use kilowatt-hours for electrical power in the US and it's the measure most readers will be familiar with. I was more poking fun at our haphazard adoption of some but not all SI units. When I was in the Corps, we measured distance in meters, weight in pounds, human height in inches, and altitude in meters unless you were communicating with an aircraft which had to be converted to feet.

01-24-2014, 04:34 AM   #44
scc

Join Date: Mar 2013
Re: Thaumaturgic Automata and Draw Power

Quote:
 Originally Posted by whswhs No. Just no. That's completely contrary to the physics. A power line does not supply kWs; it supplies kW. kWs is not "kW a second," it's "kW sustained over a time of a second" or "kw times seconds." If it were "kW a second" the notation would be "kW/s." One is multiplying; the other is dividing. And talking about "kW a second" is nonsense in this context. The kW is not a unit of energy; it's a unit of power. The unit of energy is the kJ (or kWs). A power line that supplies 360 kW is supplying 360 kJ a second; the "a second" is already there, built into the "kW." (That is, 360 kJ/s = 360 kWs/s = 360 kW.) Bill Stoddard
I thought we had covered the bit about kW/s being the change in wattage before, or am I wrong?

And while my terminology might be off, the point stands that a kWs isn't something delivered by a battery or other stored power source

01-24-2014, 09:32 AM   #45
vitruvian

Join Date: Aug 2004
Re: Thaumaturgic Automata and Draw Power

Quote:
 Originally Posted by scc I thought we had covered the bit about kW/s being the change in wattage before, or am I wrong? And while my terminology might be off, the point stands that a kWs isn't something delivered by a battery or other stored power source
No, it really doesn't, since a kWs is a unit of energy equivalent to a kJ, and batteries and other stored power sources can deliver energy, and can be rated in terms of the total energy stored.

01-24-2014, 09:45 AM   #46
whswhs

Join Date: Jun 2005
Re: Thaumaturgic Automata and Draw Power

Quote:
 Originally Posted by scc I thought we had covered the bit about kW/s being the change in wattage before, or am I wrong? And while my terminology might be off, the point stands that a kWs isn't something delivered by a battery or other stored power source
The point is that change in wattage, though it is possible to define as a physical unit, is not a variable that has a lot of actual use in physics or engineering.

As for batteries, vitruvian is right. In fact, batteries characteristically have a standard voltage that they deliver (it's a function of the metals that the two electrodes are made of); and batteries are rated for their total stored capacity in units of ampere-seconds (a 10-As battery could deliver 10 A for one second, or 1 A for 10 seconds, or 10 mA for 1000 seconds). So a battery has, say, 1.5 V x 100 As = 150 Vas = 150 Ws (since a watt is a volt times an ampere) = 0.15 kWs = 0.15 kJ (since a joule is the energy you deliver if you have a power flow of a watt sustained over a second). Or, since an As is a coulomb (the unit of charge), 1.5 V x 100 As = 1.5 V x 100 C = 150 VC = 150 J = 0.15 kJ.

The unit of kWs, or kJ, isn't explicitly stated for the battery, but it follows from what is stated and from the definitions of the units.

Bill Stoddard

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