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#191
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Power on hills.
Frank Krygowski wrote:
On Monday, December 24, 2018 at 10:36:01 PM UTC-5, John B. Slocomb wrote: On Tue, 25 Dec 2018 03:27:54 +0000 (UTC), Ralph Barone wrote: John B. Slocomb wrote: On Tue, 25 Dec 2018 02:16:08 +0000 (UTC), Ralph Barone wrote: James wrote: On 24/12/18 8:15 pm, John B. Slocomb wrote: On Sun, 23 Dec 2018 19:48:09 -0600, AMuzi wrote: On 12/23/2018 7:42 PM, John B. Slocomb wrote: Most trades or industries have their own esoteric language. Irrigation is often described in acre-feet, horses race over furlongs, bicyclists describe their power output in something other then the traditional "horse power" :-) In calculating how many head of stock you can feed from an area of land, a common measure is "dry sheep equivalent" or DSE. A ewe that is not producing milk is a dry sheep. 10 DSE per cow is the stocking rate for cows. We can support about 1 cow per hectare, or 10 DSE per hectare. You left out gear inches. Yes I did. I reckoned it might be a little complicated what with the 50 inch high wheelers and the 26 inch "low wheeler"mountain bikes, etc. Although the high wheelers were pretty easy to calculate :-) What about "gauge" as in 8, 10 & 12 gauge? Being the number of spheres of lead with a particular bore diameter that weigh a pound. "Gauge" annoys me because it just refers you to some other arbitrary thing. Put a 12 gauge shotgun shell, a length of 12 gauge copper wire and piece of 12 gauge sheet aluminum side by side and play "what do these things have in common?" :-) A "gauge" isn't something it is a term for measuring against some standard, or another, weight of a lead ball, diameter of a wire or thickness of a sheet . In plastering a wall one "gauges" the plaster by mixing specific quantities :-) cheers, John B. My point exactly. Well, one could refer to sheet metal in inches or mm. The Air Force did when referring to sheet aluminum used on aircraft. Wire is measured in mm here and the British refer to a "12 bore" gun and the French say "un fusil de calibre 12". I suppose we could also discuss the "system" used for women's clothing sizes, at least in the U.S. My wife wears a size 7... but seven _what_? And it turns out, one company's size 7 is not the same as another company's size 7. I've heard that the pricier brands make their size 7s a bit larger so some women can feel proud that they fit into a smaller size than usual. - Frank Krygowski Women's clothing sizes? They just take random tags and sew them on the completed product. If you judged by the sizing on the labels, you'd think that I had at least three wives. I don't even buy clothes for her unless she's there to try them on first. |
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#193
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Power on hills.
On Friday, December 21, 2018 at 5:14:21 PM UTC-8, jbeattie wrote:
On Friday, December 21, 2018 at 5:00:57 PM UTC-8, James wrote: On 22/12/18 7:25 am, wrote: At low speeds - those below 100 mph of so, aerodynamic drag really isn't a large loss unless you're playing for real small power such as that developed by a human over relatively long periods of time. Just as a demonstration. 30 square feet of frontal area coefficient of drag of 0.5 This is similar to a family car F = 0.5 C ρ A V^2 A = Reference area as (see figures above), m2. C = Drag coefficient (see figures above), unitless. F = Drag force, N. V = Velocity, m/s. ρ = Density of fluid (liquid or gas), kg/m3. (dry air at 70 degrees F ~ 1.2) .5 x .5 x 1.2 x 30 x 27 m/s (60 mph) = 243 N .5 x .5 x 1.2 x 30 x 45 m/s (100 mph) = 337 N Whereas the power to accelerate the mass of a car which is about 2200 lbs is huge. KE = ½mv² Ignoring the mixture of units, (you used 30 sq. feet without converting to sq. metres), you also forgot to square the velocity. The difference in force between those two speeds is huge. 30 sq. ft = 2.8 sq. m 0.5 x 0.5 x 1.2 x 2.8 x 27 x 27 = 612 N 0.5 x 0.5 x 1.2 x 2.8 x 45 x 45 = 1701 N The difference in power to maintain those speeds is even greater (proportional to V^3); 612 x 27 = 16.5 kW 1701 x 45 = 76.5 kW You also talk about power to accelerate, but give an energy equation, and include an imperial mass value in an otherwise metric discussion. 364.5 kJ to accelerate to 27 m/s 1012.5 kJ to accelerate to 45 m/s (ignoring aerodynamic drag) 22 seconds travelling at 27 m/s will require the same energy as the automobile has in kinetic energy. 13 seconds travelling at 45 m/s will require the same energy as the automobile has in kinetic energy. Now how huge is the power required to accelerate compared with the power required to maintain such speeds? Exactly 12. No, 13. The speed of light? Wait . . . now its coming to me.. Blue. God bless Nikki Terpstra (love him or hate him) https://www.velonews.com/2018/04/new...lassics_462590 -- Jay Beattie. I was really impressed with Gerant Thomas in the last Tour. On the Paris-Roubaix stage he looked in total control. His target was time and not finishing order. |
#194
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Power on hills.
On Tue, 25 Dec 2018 07:12:14 -0800 (PST), Frank Krygowski
wrote: On Monday, December 24, 2018 at 10:36:01 PM UTC-5, John B. Slocomb wrote: On Tue, 25 Dec 2018 03:27:54 +0000 (UTC), Ralph Barone wrote: John B. Slocomb wrote: On Tue, 25 Dec 2018 02:16:08 +0000 (UTC), Ralph Barone wrote: James wrote: On 24/12/18 8:15 pm, John B. Slocomb wrote: On Sun, 23 Dec 2018 19:48:09 -0600, AMuzi wrote: On 12/23/2018 7:42 PM, John B. Slocomb wrote: Most trades or industries have their own esoteric language. Irrigation is often described in acre-feet, horses race over furlongs, bicyclists describe their power output in something other then the traditional "horse power" :-) In calculating how many head of stock you can feed from an area of land, a common measure is "dry sheep equivalent" or DSE. A ewe that is not producing milk is a dry sheep. 10 DSE per cow is the stocking rate for cows. We can support about 1 cow per hectare, or 10 DSE per hectare. You left out gear inches. Yes I did. I reckoned it might be a little complicated what with the 50 inch high wheelers and the 26 inch "low wheeler"mountain bikes, etc. Although the high wheelers were pretty easy to calculate :-) What about "gauge" as in 8, 10 & 12 gauge? Being the number of spheres of lead with a particular bore diameter that weigh a pound. "Gauge" annoys me because it just refers you to some other arbitrary thing. Put a 12 gauge shotgun shell, a length of 12 gauge copper wire and piece of 12 gauge sheet aluminum side by side and play "what do these things have in common?" :-) A "gauge" isn't something it is a term for measuring against some standard, or another, weight of a lead ball, diameter of a wire or thickness of a sheet . In plastering a wall one "gauges" the plaster by mixing specific quantities :-) cheers, John B. My point exactly. Well, one could refer to sheet metal in inches or mm. The Air Force did when referring to sheet aluminum used on aircraft. Wire is measured in mm here and the British refer to a "12 bore" gun and the French say "un fusil de calibre 12". I suppose we could also discuss the "system" used for women's clothing sizes, at least in the U.S. My wife wears a size 7... but seven _what_? And it turns out, one company's size 7 is not the same as another company's size 7. I've heard that the pricier brands make their size 7s a bit larger so some women can feel proud that they fit into a smaller size than usual. - Frank Krygowski Apparently dress sizes are related to body dimensions and U.S. sizes are larger then U.K. sizes :-) https://www.hitched.co.uk/wedding-pl...chart_1433.htm http://www.sizeguide.net/size-guide-...ize-chart.html My wife ignores sizes and makes most of her clothes... she enjoys sewing :-) cheers, John B. |
#195
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Power on hills.
On Tue, 25 Dec 2018 17:37:07 +0000 (UTC), Ralph Barone
wrote: Women's clothing sizes? They just take random tags and sew them on the completed product. If you judged by the sizing on the labels, you'd think that I had at least three wives. I don't even buy clothes for her unless she's there to try them on first. The last time I shopped for jeans, I tried on a pair that I'd have liked better a bit looser, so I tried the next larger size in the same brand and style -- and I couldn't even put a leg into them. That's why that was the last time I shopped for jeans. I've been making my own for decades. Wish I could hire a seamstress to do it for me -- I'm about two years behind. I know there is more than one in the county, but they don't advertise. -- Joy Beeson joy beeson at comcast dot net http://wlweather.net/PAGEJOY/ |
#196
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Power on hills.
On Wed, 26 Dec 2018 23:42:17 -0500, Joy Beeson
wrote: On Tue, 25 Dec 2018 17:37:07 +0000 (UTC), Ralph Barone wrote: Women's clothing sizes? They just take random tags and sew them on the completed product. If you judged by the sizing on the labels, you'd think that I had at least three wives. I don't even buy clothes for her unless she's there to try them on first. The last time I shopped for jeans, I tried on a pair that I'd have liked better a bit looser, so I tried the next larger size in the same brand and style -- and I couldn't even put a leg into them. From what I see "modern women" wear stretch jeans. That's why that was the last time I shopped for jeans. I've been making my own for decades. With copper rivets in? Wish I could hire a seamstress to do it for me -- I'm about two years behind. I know there is more than one in the county, but they don't advertise. cheers, John B. |
#197
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Power on hills.
On Thu, 27 Dec 2018 13:44:07 +0700, John B. Slocomb
wrote: With copper rivets in? Leaving out the copper rivets is a good reason to make your own. Levi Strauss had a good reason for using them, but stretch-jean makers were never told what it was. Copper rivets do disguise the lumps created by cutting pockets the wrong shape. -- Joy Beeson joy beeson at comcast dot net http://wlweather.net/PAGEJOY/ |
#198
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Power on hills.
On Thu, 27 Dec 2018 22:08:11 -0500, Joy Beeson
wrote: On Thu, 27 Dec 2018 13:44:07 +0700, John B. Slocomb wrote: With copper rivets in? Leaving out the copper rivets is a good reason to make your own. Levi Strauss had a good reason for using them, but stretch-jean makers were never told what it was. Copper rivets do disguise the lumps created by cutting pockets the wrong shape. When I was a kid "dungarees", denim work trousers, were standard wear for boys... except for school where they were not allowed... But no rivets. Instead there were short sections of double sewing to strengthen the "corners". I never saw the narrow legged Levis, with rivets, until I left home and went to school in Florida. cheers, John B. |
#199
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Power on hills.
Joy Beeson wrote:
On Thu, 27 Dec 2018 13:44:07 +0700, John B. Slocomb wrote: With copper rivets in? Leaving out the copper rivets is a good reason to make your own. Levi Strauss had a good reason for using them, but stretch-jean makers were never told what it was. Copper rivets do disguise the lumps created by cutting pockets the wrong shape. Joy, you are truly a unique gift to this newsgroup. |
#200
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Power on hills.
On Wednesday, December 26, 2018 at 8:42:20 PM UTC-8, Joy Beeson wrote:
On Tue, 25 Dec 2018 17:37:07 +0000 (UTC), Ralph Barone wrote: Women's clothing sizes? They just take random tags and sew them on the completed product. If you judged by the sizing on the labels, you'd think that I had at least three wives. I don't even buy clothes for her unless she's there to try them on first. The last time I shopped for jeans, I tried on a pair that I'd have liked better a bit looser, so I tried the next larger size in the same brand and style -- and I couldn't even put a leg into them. That's why that was the last time I shopped for jeans. I've been making my own for decades. Wish I could hire a seamstress to do it for me -- I'm about two years behind. I know there is more than one in the county, but they don't advertise. -- Joy Beeson joy beeson at comcast dot net http://wlweather.net/PAGEJOY/ They really are available. You just have to go to hardware stores and not clothing retailers. https://dungarees.com/carhartt-10208...B&size=&cid=73 |
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