It’s amazing the the colonies didn’t adapt the metric system shortly after the revolutionary war, since the metric system was already around. The French Charleville muskets used by many soldiers in Washington’s Continental army had metric screws in the locks. But then, we didn’t adapt the French language either.
A liter is the volume of a 10 cm cube, but what’s the name of the volume of a one meter cube?
If you know this without looking it up, you probably solve crossword puzzles as a hobby.
Stere? I think I have seen that in a crossword…
;-]
Assuming you mean a cube with each linear dimension of 1 meter, then the volume is 1 cubic meter, or 1 m³ or 1000 Liters, or 1 kL
Stere is correct. It’s like the metric cord, used to measure firewood.
It comes from the same Greek word from which we get the word “stereo”.
could this discussion please be brought back more on topic? Thanks.
A lot of European cars and motorcycles had the engine’s power given in Pferdestärke or PS, also known as the metric horsepower. They are getting away from this unit because it’s based on the kilogram as a force unit and replacing it with the kilowatt which uses the Newton as a force unit.
The kilogram is a unit of mass, using it as a force unit is improper.
Pferde means horse in German. Stärke is German for strength.
@bing Rather than convert to 250 volts d.c., let’s go to 25 Hz a.c. When I was a kid, the next town to our west had 25hz power. A common radio was designed for 120 volts 60 Hz a c. or 120 volts d c. In fact, very little will operate on 25 Hz power except incandescent light bulbs and even these bulbs flicker.
Buildings that have three phase power have lights that operate at 277 volts a c. This is the voltage between one phase and ground.
I’m sure that there is some road speed where the three phase induction motor in a Tesla is getting 25 Hz AC.
Three phase motors will operate satisfactorily at 25 Hz provided the voltage is reduced in the same proportion as the frequency. A 100 hp 1800 rpm 480 volt motor at 60 Hz would require 200 volts at 25 Hz and would only turn 750 rpm while making only 41 horsepower. At low rpms, cooling sometimes is a problem and there is a torque drop off because the motor is still drawing the same amps so you still have the same I^2 * R losses in the winding which is a larger percentage of the terminal voltage. Some variable frequency drives kick up the voltage a little at low Hz to compensate for this.
A wye connected 480 volt power system will provide 277 volts from each leg to neutral.
A wye connected 208 volt power system will provide 120 volts from each leg to neutral and is very common in commercial use.
Most industrial users of 480 volt have a separate lighting transformer to provide 120/240 single phase because even industrial plants have to have wall sockets for 120 volts. How you gonna make coffee in the break room and office otherwise? How you gonna run the refrigerator and Coke machine?
You know, there’s an old saying, “if it aint broke, don’t fix it” and I think it applies to the U.S.'s power system.
Besides, volts, amps, and watts already are metric units or more accurately, the Système international (d’unités). (formerly known as the kilogram-meter-second system)
Um, it was a joke guys. Not serious.
My 20023 Bonneville has the E/M button.
Why hasn’t the US converted to metric? Several reasons. Mostly the US units are based on practical needs, rather than the size of the earth:
Construction. People come in Avoirdupois (the real name of the US system) or Foot-Pound-Second (FPS) sizes, not metric sizes. The foot is a very practical unit for building houses and other buildings, 8 ft is the height of a room (stud, wall panel, etc). Doors are normally 7 ft by 3 ft. But try building a house to fit people in metric and you are doing long division or punching a calculator. Also note that existing houses need the FPS parts for replacement or adding on.
Sewing uses the yard and the foot because of the sizes of people.
Plumbing: The new pipes and fixtures have to fit what is already there. So any replacement or add-on parts have to be in FPS sizes.
Cooking: Recipes are designed around natural standards (e.g. the egg). I have never found any metric eggs. The teaspoon, tablespoon, cup, and other standard cooking measures are based on the size of the egg and the easy ability to double, triple, halve, or third a recipe. In metric you weigh everything and use long division or a calculator.
Automotive: The parts have to fit the car you already have.
A few notes:
Why do we use the second in metric? It is not based on 10. It is 1/86400 of one rotation of the earth. Why didn’t they make metric hours (10 in a day) and subdivisions of powers of 10? Of course, if they had done this, the electrical, power, and motion units in the SI would all be different.
1.5 feet? That’s a cubit.
I once saw velocity expressed in furlongs per fortnight.
I read the story of the Gimli glider. I even applied part of it to driving. I found a way to “sideslip” a car to slow it down without brakes the way I used to sideslip a sailboat.
There is a reason they don’t use 277V for lighting. An electrician would be needed to change a dead bulb. I read about a time the installers connected the 277 V and 120 V three-phase transformers to the wrong service entrances of a new building. The building inspector turned on the fluorescent lights in a hall and all of the tubes exploded.
I once diagnosed a malfunctioning new treadmill in a human performance lab to the 3-phase power outlet being hooked up with the B and C phases switched. The treadmill motor ran backwards.
I would be very angry if they ever changed power in the US away from 60 Hz. I still have a 1961 Collaro Conquest record changer that I regularly use to listen to my record collection. Its speed depends on the power line frequency. Yes, I stocked up on styli and drive wheels.
I recently bought some newly released records that didn’t work on my Collaro. The center holes are supposed to be 5/16 inch on a small hole record, but they made them 1/4 inch. They would not fit on the spindle. I gently used a reamer with a vacuum cleaner to enlarge the holes.
One BIG misuse of metric units for years is measuring the stylus force of a record player in grams. A gram is a unit of mass, not of force. The Germans started this, because they once had a unit of weight (force) called the pfund which was the amount of force created by the weight of one gram of mass at sea level. The problem occurred when this was translated into other languages. Most record players ended up with tracking force settings calibrated in grams.
FPS measure does have a unit of mass. It is the slug, and weighs exactly 32 pounds at sea level.
In 1997, one or our Mars probes crashed into the planet instead of soft landing because the engineers designing the trajectory used metric, but the engineers designing the thrusters used FPS. Nobody bothered to convert.
When water is used, a pint is a pound and a fluid ounce weighs one ounce. Most items used in cooking have specific gravity values similar to that of water.
Computer people still use base 16 for internet IP addresses and for color values in websites. The digits are 0123456789abcdef.
I have a drill box that has the SAE fractional or letter, decimal inches, and decimal metric by the hole for each bit. It also has sets of metric and SAE bits. Of course, the metric bits have no SAE number.
The National Electrical Code for several years had both metric and US wire and box sizes. It dropped the metric sizes a few years ago because people were making mistakes because they were there. In US wire sizes, a larger number is a smaller wire.
OK fine, If it is on the internet it has to be true.
If I see someone ahead of me doing a 'sideslip maneuver ’ I am calling to report a intoxicated driver.
Relax. It doesn’t involve skidding.
The main use is to stop a car when the brakes have failed. First (after trying the emergency brake) downshift to get the speed down, one gear at a time, until you get to first. When you are slow enough to be in first, then get into gravel, turn uphill if you can, or ess the car (the sideslip) on level road to use up the remaining energy. Put in neutral, and then park when the car stops.
I use a variant of sideslip when a car moves into my front safety space while I am on cruise control. It puts enough drag on the car for me to regain my following distance without having to set the cruise control again. Other drivers would not notice it as anything other than slowly moving from near one side of the lane to near the other and back.
Cruise control set, moving back and forth in the lane and car slows , really?
Actually I’ve never had my brakes fail but I have driven in heavy traffic once with a bum master cylinder.
I had brakes fail in a work truck while approaching a stop sign, it created the illusion that you felt like you were actually going faster, luckily no cars in the intersection and limped it back to the shop using the manual transmission and parking brake.
In the SI system, the kilogram of mass is a basic unit and the newton of force is a derived unit.
In the FPS system it’s backwards, the unit of force it the basic unit and the unit of mass is a derived unit.
The slug is the amount of mass that would weigh one pound in a gravity of 1 ft per second per second.
Since the earth’s gravity accelerates things at 32.2 ft per second per second, a slug weighs 32.2 pounds.
A kilogram weighs 9.8 newtons on earth because earth’s gravity is 9.8 meters per second per second. On a planet that has a gravity of exactly one meter per second per second, a kilogram of mass would weigh one newton.
The SI system also likes to name the derived units after pioneering scientists. Voltaire, Watt, Ampere, Faraday, Henry, Maxwell, Ohm, Newton…
I find it ironic that our tires are sized by both metric and US customary units. The rim diameter is in inches but the width is in mm.
When the cruise control is set, moving back and forth in the lane has two effects:
The path of the car is longer than the path of the car ahead, increasing the space between two cars going the same speed.
There is an increased drag due to the front wheels being at a slight angle to the road speed.
When the cruise control is set, moving back and forth in the lane has two effects:
The path of the car is longer than the path of the car ahead, increasing the space between two cars going the same speed.
There is an increased drag due to the front wheels being at a slight angle to the car velocity.
You have to do some radical zig-zagging to have a noticeable effect on distance between cars.
60 mph times the cosine of 15 degrees is 58 mph.
60 mph times the cosine of 5 degrees is 59.8 mph.
When sailboat racing on a downwind run, if heading up from the rhumb line 15 or 20 degrees adds just one mile per hour to your boat’s speed, it’s worth it
I say ’ Malarkey ’ and please keep this silly idea to yourself. It makes more sense to hit cancel then resume then make drivers around you wonder what is that person doing.