A comment on weight and mass

[Morrus]

A stone is a common Imperial measurement here in the UK - it is used to measure the weight of people (I'm 11-and-a-half stone). It's 14lbs. Like a foot is 12 inches. It has nothing to do with mass or bulk.

 

[Sniperfox47]

As much as I hate the thought of trying to do physics in imperial units, I can understand the benefit for some people.

It shouldn't be that hard to adopt weights to fit varying planets, as long as the unit of gravity of the planet is a ratio to the baseline used for the items weight. For example if the book assumes earth like gravity (G0=~9.81 m/s^2) for the equipment, a planet (G1) with two times the mass should have approximately twice the attractive force (G1=~2xG0) so long as the planet is much larger than your equipment. So just double all the weights (weight is force, and if the gravitational acceleration doubles and the items mass stays the same, the force doubles as well). If the planet has 3.6x the gravity of earth multiply the items weight by 3.6x. It's that simple.

While the size of a planet and it's mass aren't directly related I can't see too many instances where you'd land on a superdense rock the size of a neighborhood block, and if you are then gravity wouldn't behave quite the way we're used to here on earth anyways. If there were rules for calculating gravity and it's effects on any possible astral body he'd need to make the rulebook thicker than a university textbook.

 

[pedr]

(Didn't see the next page)

 

[Sniperfox47]

(in common usage - doctors use kilograms)

Kilograms isn't a measure of weight though! Newtons are weight, kilograms are mass.

 

[Morrus]

As much as I hate the thought of trying to do physics in imperial units, I can understand the benefit for some people.

It shouldn't be that hard to adopt weights to fit varying planets, as long as the unit of gravity of the planet is a ratio to the baseline used for the items weight. For example if the book assumes earth like gravity (G0=~9.81 m/s^2) for the equipment, a planet (G1) with two times the mass should have approximately twice the attractive force (G1=~2xG0) so long as the planet is much larger than your equipment. So just double all the weights (weight is force, and if the gravitational acceleration doubles and the items mass stays the same, the force doubles as well). If the planet has 3.6x the gravity of earth multiply the items weight by 3.6x. It's that simple.

While the size of a planet and it's mass aren't directly related I can't see too many instances where you'd land on a superdense rock the size of a neighborhood block, and if you are then gravity wouldn't behave quite the way we're used to here on earth anyways. If there were rules for calculating gravity and it's effects on any possible astral body he'd need to make the rulebook thicker than a university textbook.

The way to do it is to adjust the character, not every object. You adjust speed and jump distances, etc., at the top level rather than forcing players to recalculate everything on the fly. That's easy if you use broad bands of gravity - zero, low, terrestrial, high, super-high.

 

[kinem]

To be fair, there is such a thing as pound (mass), a unit of mass that weighs one pound (force) in 1 g. I prefer sci-fi in SI, though.

 

[Sniperfox47]

The way to do it is to adjust the character, not every object. You adjust speed and jump distances, etc., at the top level rather than forcing players to recalculate everything on the fly. That's easy if you use broad bands of gravity - zero, low, terrestrial, high, super-high.

I'll be interested to see how that works. I guess I just assumed the rules would apply to every object (including the character themself) since it would trivialize trying to deal with unattended objects. If you draw it up as adjustments to a character I don't know how you'd be able to handle interactions of effects such as move force (or an equivalent psionic power) with objects not held by a player.

It also bugs me on principle saying "Your character can carry twice as much weight" when you can carry the same amount of weight, everything just weighs half as much.

To be fair, there is such a thing as pound (mass), a unit of mass that weighs one pound (force) in 1 g. I prefer sci-fi in SI, though.

True, but there are quite a few physics constants that specifically assume you're using SI. Sure there are imperial equivalents to them but they're much harder to track down than the SI version. And since SI is a subset of metric they're mostly inter-compatible.

 

[Morrus]

I'll be interested to see how that works. I guess I just assumed the rules would apply to every object (including the character themself) since it would trivialize trying to deal with unattended objects. If you draw it up as adjustments to a character I don't know how you'd be able to handle interactions of effects such as move force (or an equivalent psionic power) with objects not held by a player.

It also bugs me on principle saying "Your character can carry twice as much weight" when you can carry the same amount of weight, everything just weighs half as much.

Sure; and you know what - you're right. I should try not to stray from the original mission statement of scientific verisimilitude (obvious sci-fi stuff notwithstanding, of course) in fvaour of simplicity.