My experience with U.S. students is that they are having a much harder time making sense of the imperial system (that they are used to) than doing problems in metric, even though they don’t use it in everyday life.
First off, you linked to a list of english measures which are not used in the US. Nobody uses fathoms or barleycorns.
Here is the list of actual US customary units: https://en.m.wikipedia.org/wiki/United_States_customary_unit...
Second, none of that is relevant to landing on Mars.
The only problem space where metric has an advantage is in converting between meters, kilometers and millimeters.
That’s great, and it’s easy to learn. But it doesn’t suddenly make all problems of distance easier to solve.
If I am traveling toward Mars at 47 meters per second it doesn’t help me to know that is also .047km per second. And converting to kilometers per hour involves using base 60 twice anyway because metric time is unwieldy.
In reality none of your measurements are going to be nice round numbers. Mentally converting from meters to km might be nice sometimes but it’s essentially a party trick.
It won’t help the lander make decisions. The hardware doesn’t inherently work in base 10.
Does NASA mix meters and kilometers? Isn’t that the same problem that destroyed the Mars Climate Orbiter?
The fact is the units are irrelevant beyond just being defined and used consistently.
Also, I can’t think of a situation where I need to convert miles to feet. My bike ride is six miles, I’m never going to express that in feet. If I need to describe the size of a thing in a room I will probably use feet, maybe inches if it is small. Probably not feet and inches. I wouldn’t use miles at all. Easy conversion between those units just isn’t a problem that comes up. It’s more important to me to have reasonably sized units and that the person I am communicating with understands them.
How many pounds does a cubic feet of water have?
How many BTUs do you need to heat 10x10x3 ft water pool 20 degrees F?
How much work in ft-lb is done by gravity when a 10 oz mass drops from 19 yards?
How many HP are needed to rais 2400 lbs 74 inches in 30 sec?
It is obvious you have 0 experience doing back-of-the-envelope calculations for scientific or engineering purposes. It is a no-contest between the metric and the imperial systems.
Yes it does. It means you can immediately sanity-check your numbers even if you don't have a good sense of what meters and kilometers are, because you have that base/kilo relationship.
> My bike ride is six miles, I’m never going to express that in feet.
You can eyeball how fast you're going in feet per second and have a rough idea of how long your ride is going to take. Or rather you could if you had any idea of how long your ride was in feet. There are lots of little everyday things that just become much easier.
I estimate my bike ride progress in landmarks and time. Not feet per second. Did I get to the boat ramp in 20minutes? Better speed up and get to the park by 30.
But you'll have small distances and large distances and pieces from external sources who use measurements on a scale that makes sense to them. You can make your external sources do conversions themselves, but that's just moving the problem around. There will usually end up being a point, or probably several points, where you have to relate a small distance to a large distance, and wherever that happens, a human sanity check is a help.
> I estimate my bike ride progress in landmarks and time. Not feet per second. Did I get to the boat ramp in 20minutes? Better speed up and get to the park by 30.
Precisely - you have no sense of the relation between your speed and how far you can go, because you're using a terrible measurement system, and you don't even notice the how that's robbing you of the ability to develop useful intuitions.
Miles per hour is literally a measure of distance over time. If I wanted to use my GPS I could very easily determine how far I can go in a given amount of time. I can do this equally well in the metric or imperial systems, without converting to feet or meters.
The hardware doesn’t think in base 10, but having more than that in imperial makes it better?
Your document lists 12 mass units alone. I rest my case, what could possibly be more logical, convenient, and need less conversion.
If communication was your major goal, then the system that is used by 7.3 billion people on this planet would be your choice.
Great, we agree.
> Metric on the other hand sucks because none of my measurements will ever be nice round numbers.
Depends on the situation. Metric units can be useful.
> The hardware doesn’t think in base 10, but having more than that in imperial makes it better?
No, it means neither system has an advantage so just pick one. Or invent a new one that allows better hardware utilization.
> Your document lists 12 mass units alone. I rest my case, what could possibly be more logical, convenient, and need less conversion.
I don’t convert, I just pick the unit that fits the problem.
> If communication was your major goal, then the system that is used by 7.3 billion people on this planet would be your choice.
Yeah I use the metric system all the time. Just like NASA.
But one of the systems does have an advantage because it stays in base 10, whereas the other doesn't.
>> Your document lists 12 mass units alone. I rest my case, what could possibly be more logical, convenient, and need less conversion. >I don’t convert, I just pick the unit that fits the problem
But you can't if you just use the `intuitive unit', and that's the whole problem. How would you measure the amount of liquid fuel in, say, the small tank for an attitude control thruster of some probe? How does that add to the overall mass of the whole probe? Or to the force you then need to accelerate it by a certain amount? And now compared to the whole launcher?
In which units do you measure everything going on in a small wind tunnel model, and how do you compare that with the real thing?
Under which conditions do you go from fluid ounces to ounces to cups to pints to quarts to gallons (also note that, again, you not only switch units but bases)?
>Yeah I use the metric system all the time. Just like NASA.
Good for you, it solves all the problems.
That's a benefit to humans, not to hardware, which was the context in which I was speaking.
> But you can't if you just use the `intuitive unit', and that's the whole problem. How would you measure the amount of liquid fuel in, say, the small tank for an attitude control thruster of some probe? How does that add to the overall mass of the whole probe? Or to the force you then need to accelerate it by a certain amount? And now compared to the whole launcher?
Honestly? I'd probably measure it in volts. That's what the hardware is doing after all. That's my point, it doesn't help the computer to convert to base 10 and do calculations that way. Fuel level is measured in volts using binary. For a human something like grams probably makes more sense so sure, display it in those units. But that's a conversion.
> In which units do you measure everything going on in a small wind tunnel model, and how do you compare that with the real thing?
Again, volts on strain sensors. Maybe analog or maybe binary, in newtons. Again, the hardware doesn't think in units humans prefer. There has to be a conversion that doesn't use simple in-your-head math.
> Under which conditions do you go from fluid ounces to ounces to cups to pints to quarts to gallons (also note that, again, you not only switch units but bases)?
Cups, pints, quarts and gallons are all based on the ounce and powers of two. A gallon is 128oz, a half gallon is 64oz, a quart is 1/2 of a half gallon (or a quarter gallon) or 32oz (also, approximately a liter). A pint is half a quart or 1/8th of a gallon or 16oz, a cup is half a pint or 1/16th of a gallon or 8 oz. These fractional scales are really handy for converting between units in some situations. The unit fits the task at hand or you can trivially double or halve the size of the unit if needed. It's the same fractional scale and math used with the inch.
I have gone much farther here than I normally would. I don't think I can constructively explain this to you any further.
Using one universally accepted system is core idea behind metric system. Now, it looks like it is competition between two equal systems, but historically it is competition between ideas 'we should have one universal system' and 'every country/area can stay on their local systems'. Just all other legacy local systems (outside u.s. customary) disappeared.