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Looking at our new page Orders of magnitude (force) I thought it might be nice to add something "down to earth". I was thinking of the force of rain hitting the ground. Unfortunately I sort of got stuck half way though. At a diameter of 1 mm we could assume a drop to be spherical and I think a drag coefficient of 0.1 for a smooth sphere could be applied (or do we need a rough sphere at .4?). That should give us the terminal velocity in free fall. I got 0.523598775 mm3 for a volume and seem to remember 1 liter of water weighs one kg. 1 L our page says is 1 cubic decimeter. Anyone willing to lend a hand?Lisa4edit 76.97.245.5 ( talk) 00:05, 10 January 2009 (UTC)
Suggestion for (original) research: (Might make a science project for someone). I wonder if, experimentally, one could note the effect of one raindrop hitting a leaf (or some elaborate experimental raindrop target) and noting the deflection, by videography, then measuring the force needed to produce the same deflection. In physics lab we fired a 22 caliber bullet into a block of wood free to swing, and noted how far it swung with the embedded bullet, measuring the energy and from the mass, the velocity of the bullet, and compared it to a standard velocity meter which had 2 rotating paper discs a certain distance apart. Or would this deflection measurement due to a raindrop only give us energy? A leaf would be springlike, whereas the wood block was gravity restored to its original position. If there were a substance delicate enough that a falling raindrop could break it, that could be a force measurement. A delicate enough strain gauge should be able to directly measure the force. Perhaps a target attached to a phono stylus could measure the force. Edison ( talk) 20:29, 11 January 2009 (UTC)
Rather than leaves observe raindrops hitting a puffball They are constructed so that spores are released during a good rainfall. Certainly a reliable source has reported on the metrics of this phenomenon. -- Digrpat ( talk) 15:02, 13 January 2009 (UTC)
In my wanderings around wikipedia, I came upon this map of the crude death rate for different countries of the world. When you see a map like that, you have an expectation of how it will look, you expect at least some correlation with affluence. You know, Europe, the US, Canada, Australia and a few others will be really pale, while Africa would stand out sharply, and South America and Asia somewhere in between (like this map, for instance). And while it does follow some of those conventions (Africa having a high rate, for instance), there are a number of things in there that are really strange. All of Europe, besides Ireland, are fairly high on the scale. Mexico is lower than the US and Canada. In fact, the countries with the lowest rate are Mexico, Saudi Arabia, Jordan, Syria, Algeria, Libya, Venezuela, Paraguay and Ecuador. It's not exactly the list of countries you would expect to stand out in a map like that. I mean, seriously, Syria is kicking Scandinavia's ass! So what's up with that? I mean, if your country really is really dirt poor, then it seems to have a high death rate (as evidenced by Africa), but once it passes a certain threshold, it looks essentially random. But it can't be completely random, because all of Europe is one color (which would be an extraordinary coincidence). There has to be some factors lowering the score for some countries, but I can't for the life of me think of what they might be. Any one got any ideas? Belisarius ( talk) 02:04, 10 January 2009 (UTC)
-- Milkbreath ( talk) 02:26, 10 January 2009 (UTC)"This entry gives the average annual number of deaths during a year per 1,000 population at midyear; also known as crude death rate. The death rate, while only a rough indicator of the mortality situation in a country, accurately indicates the current mortality impact on population growth. This indicator is significantly affected by age distribution, and most countries will eventually show a rise in the overall death rate, in spite of continued decline in mortality at all ages, as declining fertility results in an aging population."
why the op amp is given the dual power supply? what the meaning of dual power supply? how to know weather the capacitor is charging or discharging? —Preceding unsigned comment added by KARTHICK18ECE ( talk • contribs) 11:49, 10 January 2009 (UTC)
Why do some people recuperate their abilities after a stroke? After damage of neuronal tissue, it is gone forever, isn´t it?-- Mr.K. (talk) 16:27, 10 January 2009 (UTC)
Science desk | ||
---|---|---|
< January 9 | << Dec | January | Feb >> | January 11 > |
Welcome to the Wikipedia Science Reference Desk Archives |
---|
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages. |
Looking at our new page Orders of magnitude (force) I thought it might be nice to add something "down to earth". I was thinking of the force of rain hitting the ground. Unfortunately I sort of got stuck half way though. At a diameter of 1 mm we could assume a drop to be spherical and I think a drag coefficient of 0.1 for a smooth sphere could be applied (or do we need a rough sphere at .4?). That should give us the terminal velocity in free fall. I got 0.523598775 mm3 for a volume and seem to remember 1 liter of water weighs one kg. 1 L our page says is 1 cubic decimeter. Anyone willing to lend a hand?Lisa4edit 76.97.245.5 ( talk) 00:05, 10 January 2009 (UTC)
Suggestion for (original) research: (Might make a science project for someone). I wonder if, experimentally, one could note the effect of one raindrop hitting a leaf (or some elaborate experimental raindrop target) and noting the deflection, by videography, then measuring the force needed to produce the same deflection. In physics lab we fired a 22 caliber bullet into a block of wood free to swing, and noted how far it swung with the embedded bullet, measuring the energy and from the mass, the velocity of the bullet, and compared it to a standard velocity meter which had 2 rotating paper discs a certain distance apart. Or would this deflection measurement due to a raindrop only give us energy? A leaf would be springlike, whereas the wood block was gravity restored to its original position. If there were a substance delicate enough that a falling raindrop could break it, that could be a force measurement. A delicate enough strain gauge should be able to directly measure the force. Perhaps a target attached to a phono stylus could measure the force. Edison ( talk) 20:29, 11 January 2009 (UTC)
Rather than leaves observe raindrops hitting a puffball They are constructed so that spores are released during a good rainfall. Certainly a reliable source has reported on the metrics of this phenomenon. -- Digrpat ( talk) 15:02, 13 January 2009 (UTC)
In my wanderings around wikipedia, I came upon this map of the crude death rate for different countries of the world. When you see a map like that, you have an expectation of how it will look, you expect at least some correlation with affluence. You know, Europe, the US, Canada, Australia and a few others will be really pale, while Africa would stand out sharply, and South America and Asia somewhere in between (like this map, for instance). And while it does follow some of those conventions (Africa having a high rate, for instance), there are a number of things in there that are really strange. All of Europe, besides Ireland, are fairly high on the scale. Mexico is lower than the US and Canada. In fact, the countries with the lowest rate are Mexico, Saudi Arabia, Jordan, Syria, Algeria, Libya, Venezuela, Paraguay and Ecuador. It's not exactly the list of countries you would expect to stand out in a map like that. I mean, seriously, Syria is kicking Scandinavia's ass! So what's up with that? I mean, if your country really is really dirt poor, then it seems to have a high death rate (as evidenced by Africa), but once it passes a certain threshold, it looks essentially random. But it can't be completely random, because all of Europe is one color (which would be an extraordinary coincidence). There has to be some factors lowering the score for some countries, but I can't for the life of me think of what they might be. Any one got any ideas? Belisarius ( talk) 02:04, 10 January 2009 (UTC)
-- Milkbreath ( talk) 02:26, 10 January 2009 (UTC)"This entry gives the average annual number of deaths during a year per 1,000 population at midyear; also known as crude death rate. The death rate, while only a rough indicator of the mortality situation in a country, accurately indicates the current mortality impact on population growth. This indicator is significantly affected by age distribution, and most countries will eventually show a rise in the overall death rate, in spite of continued decline in mortality at all ages, as declining fertility results in an aging population."
why the op amp is given the dual power supply? what the meaning of dual power supply? how to know weather the capacitor is charging or discharging? —Preceding unsigned comment added by KARTHICK18ECE ( talk • contribs) 11:49, 10 January 2009 (UTC)
Why do some people recuperate their abilities after a stroke? After damage of neuronal tissue, it is gone forever, isn´t it?-- Mr.K. (talk) 16:27, 10 January 2009 (UTC)