Science desk | ||
---|---|---|
< May 5 | << Apr | May | Jun >> | May 7 > |
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. |
Since lifting an object increases it's energy, wouldn't it therefore increase it's mass? And wouldn't this in turn increase it's energy even further, making a cycle? Since energy is rest mass + kinetic+other forms of energy etc. Also: Should I be using it's or its in my first sentence? That one has always bugged me, since I am showing ownership of the property, but I'm not sure if ownership transfers over to pronouns. If they don't then the un-contracted form being it is, would not make sense in that sentence. —Preceding unsigned comment added by 141.218.35.51 ( talk) 00:47, 6 May 2009 (UTC)
Thanks for the quick response to my grammatical question, I knew it felt wrong. "when energy of any kind is added to a resting body, or to a system of bodies, the increase in the mass as seen by a single observer (or as seen from any given inertial frame) is equal to the energy added, divided by c2." This was taken from the energy-rest mass equivalence article here. Wouldn't this cause the lifted object to experience increased mass? —Preceding unsigned comment added by 141.218.35.51 ( talk) 01:19, 6 May 2009 (UTC)
So I don't really understand where the mass is contained, if it is the gravitational field, what is the form in which it takes? 141.218.35.51 ( talk) 03:45, 6 May 2009 (UTC)
With regard to the infinite cycle problem, you have to be careful about how you are changing the potential energy of the object in your thought experiment. If I am holding a book on earth, and you define the system to be me+the book+earth, there is no energy being added to the system when I raise the book higher off the ground, I'm simply converting the electromagnetic potential energy stored in my muscles into another form of energy. So in that example, the relativistic mass does not change. Adding energy to the system would mean transferring it from an outside source, for example hitting the planet with light from the sun, or redefining the system to only encompass the Earth + the book. Truthforitsownsake ( talk) 12:47, 6 May 2009 (UTC)
To expand on the prior topic: Suppose we start with two masses in space which are gravitationally attracted to each other. As they approach they each gain kinetic energy and loose potential energy (potential energy becoming negative). When they collide, they merge and the potential energy becomes heat which eventually radiates away. With that loss of energy is a loss of mass as observed from outside the system. Now, suppose I were to descend into their gravitational well and measure their mass from there. Would my measurements equal the sum of the original two masses? To put it another way, would my observations from within the gravity-well be different than those at a distance? I know general relativity predicts gravitational time dilation, but what else changes? (..in layman's terms please, sans any stress-energy tensors and the like.) -- Tcncv ( talk) 04:21, 6 May 2009 (UTC)
q1-if light bulbs are connected to other bulbs just like in a series circuit such as in Christmas lights,they get dimmer .why is that? q2-if light bulbs are connected to other bulbs just like in a parallel circuit such as in household wiring .they stay bright .why? q3-how long light bulb last ?what happens to light bulb when it gives it's last glimmer I HAVESEARCHED EVERYWHERE google ,wikipedia ,my textbooks but i couldn't find it —Preceding unsigned comment added by Srijan89 ( talk • contribs) 07:40, 6 May 2009 (UTC)
Recently, in the last week, there were two occurences of the presence of a noisy fly in my house. The first, was precisely five days ago where the presence of the fly was known to me for sometime. During the morning and afternoon, it appeared that the fly was attracted to food, like other flies. It was extremely noisy, large and slow, making it easy to kill. However, it was most difficult to determine its location, as often it would sit still unless disturbed. At night, I happened to notice the fly, flying around a light source; it seemed quite far away from my position. I walked along (in my house) with no notice of it, for at least 10-15 metres. Then, to my surprise, I found it idle on my neck. I could not see it and therefore could not determine the exact second when it landed there, but having placed my hand on my neck alarmed me. The fly, to this sudden movement, responded by making a loud buzzing noise - extremely loud to my ear considering that it was on my neck. Within an instance, I noticed it on the wall in front of me. It came a surprise to me that a fly could travel such great distance in so little time, when, in my experience, such flies had been easy to kill and recognizable by their lack of agility. I approached the fly, and within an instant, killed it.
The next time that the presence of such a fly was beknownst to me, was merely a few hours ago. It seemed that the fly was attracted to any light source, often flying near the windows through which the light of the sun shone. It was therefore easy for me to trap the fly behind some curtins. Upon doing this, I heard a great buzzing noise - although I was certain that this fly was actually a fly, rather than a bee. The fly seemed to fly at a low altitude, making it somewhat inconspicuous. In the end, however, I killed it, in the same manner as that of the previous incident.
Based on the previous observations (concisely: loud buzzing noise, slow to move but quick in flight, large, inconspicuous, attracted to light - all in comparison to the average fly), what is the exact species of this fly? Based on my understanding of flies, I would predict this fly to be either a deer fly or a horse fly. However, despite being on my neck for sometime, the fly did not bite me. On the other hand, the flies which I have described seem more aggressive compared to other flies. It also seems that the ratio between the presence of these flies in my house, to the presence of the average fly in my house, is about 1:1. Furthermore, rarely is there such a fly during the summer season. Does anyone have any specific ideas regarding the species to which this fly belongs and the exact name of this fly? Thankyou for any remarks, and apologies for the somewhat long and narrative-like question that I am asking. -- PS T 10:09, 6 May 2009 (UTC)
Sounds to me like 1 of the Calliphorid flies or "dumb house flies". They would naturally overwinter in the burrows of animals but your walls or basement seem fine to them. As they warm up, like all ectotherms, they become active. They are attracted to light then since it would mean the way out of the animals burrow. As to why they landed on you, well they do lay thier eggs on other bugs and even eartworms but i doubt they thought you were one of thier potential hosts. Likely just seeking warmth. The Buzzing is likely just a predator avoidance thing, annoying yes, but harmless and effective. Most adults are pollen feeders. I would leave a light on near the door then just scoop the little buggers outside in the a.m. to continue thier important work!
I know the above is unsourced but hey, you asked!!! 67.193.179.241 ( talk) 15:34, 6 May 2009 (UTC) Rana sylvatica
Hi. In the 7.62x39mm cartridge (for example) what does the 7.62 stand for? I thought it was the bullet diameter, but apparently it's not. Also, why do they use 2 measurements instead of 1, like 9mm or .45? And what is shown by those specifications (9mm etc)? Thanks in advance —Preceding unsigned comment added by 122.255.2.65 ( talk) 11:59, 6 May 2009 (UTC)
First sorry for the title that doesnt says anything, but english is not my first language and I hope that you will understand what I am trying to know.The question:Why does a Cell-phone when lying on a table and ringing(vibrating) move? The phone should represent an Inertial frame and should not move as long as no force from outside is acting on it or am I wrong? Please explain. Thank You. DST —Preceding unsigned comment added by DSTiamat ( talk • contribs) 12:51, 6 May 2009 (UTC)
"So, if the internal little weight moves quickly in one direction, the rest of the phone will move slightly in the other"-Does this not violate the conservation of momentum? I understand that THIS IS conservation of momentum but if u see the Phone as one sytem who suddenly begins moving?Or should it not be seen this way? Explain please —Preceding unsigned comment added by DSTiamat ( talk • contribs) 13:51, 6 May 2009 (UTC)
The comparation is not the best because a car INTERRACTS whit the road through the weels where the phone does not(vacuum etc), i think it has something to do whit the moving of its centre of mass as Tango said, the momentum in case of the car is clearly conserved ( car moves one way, earth other etc) —Preceding unsigned comment added by DSTiamat ( talk • contribs) 13:58, 6 May 2009 (UTC)
Thank you Gandalf and SteveBaker really clever guys they understood what I was actually asking.
TY, DST —Preceding unsigned comment added by DSTiamat ( talk • contribs) 15:59, 6 May 2009 (UTC)
The reason the phone doesn't end up where it started if the vibrator moves quickly in one direction and slowly back (slowlyback-QUICK-slowlyback-QUICK) is beecause the slow movements leave it STATIONARY because of friction. It's the same as a jar. if you're in a jar and hit a basketball against the glass again and again and again and again, you could slowly move in that direction. That's because when it gets back to you, you catch it slower, so that there is literally 0 movement of the glass jar (due to friction of the ground) but when you throw it against the glass the quicker movement is able to overcome friction so that you move 0.001 meters for example. Do it enough times and you end up moving in that direction. But what about in space? In space if you are strapped in the center of an object and you keep throwing a basketball at the same wall and catch it on it's rebound back to you, you will NOT budge. When you catch the basketball again strapped to the center, even if you're doing it MORE SLOWLY, there is no FRICTION that makes this "more slow" movement = 0.
In conclusion: it's quite simple: your cell phone moves because friction makes it so that a force that would normally result in slow movement in fact results in 0 movement. So whereas in a vacuum it would vibrate like this: sachay slowly to one side, quickly to the other, slowly to one side, quickly to the other (remaining in the same net location), on the table it does this: sachays quickly to one side, remains still, sachays quickly to one side, remains still, ending up moving in that direction. The "remains still" part is where the vibrator, in space, would be countering the movement it just made, as it moves back so it can make it again...
79.122.21.123 (
talk)
19:11, 6 May 2009 (UTC)
that's very long steve, could you summarize it in a sentence the way I did with m ine? 94.27.231.41 ( talk) 11:17, 7 May 2009 (UTC)
I've got a huge, hairy black spider in my kitchen with yellow and black triangle markings down its back. Anyone know what it is? Thx in advance -- Anonymous07921 ( talk) 13:41, 6 May 2009 (UTC)
Google " camel spider bite" and click on images....that guy's leg looks pretty messed up. -- Anonymous07921 ( talk) 18:58, 6 May 2009 (UTC)
I would suggest taking a picture with a digital camera; all though this portal is brilliant for just about everything i feel the best person to ask would be the old guy in your neighbourhood who has lived there all his life; he may smell a little funny and start droaning on about the war while forcing you to have a game of Dominoes for his wisdom; but he will no doubt be able to tell you what type of spider it is and if it is going to sink its fangs into your flesh!!!! Chromagnum ( talk) 05:21, 7 May 2009 (UTC)
Scientists have discovered many stars that have planets at great distance using things like stars wobbling from planet gravity or a bit of dimming from a planet "eclipsing" the star. At what range from our solar system, would our scientists be able to detect that our own solar system has planets using their current methods? 65.121.141.34 ( talk) 13:59, 6 May 2009 (UTC)
I would also imagine that it is going to depend on where you are relative to the solar plane? If you are looking down on the solar system, a planet would never move in front of the sun, making planets harder to detect and greatly reducing your range then if you are in line with that plane right? 65.121.141.34 ( talk) 15:08, 6 May 2009 (UTC)
Hi, Wikipedia
Nowadays I'm trying to figure out how a mass body behaves when changing its position normal to the earth surface and I hope you can help me in this topic and confirm the correct statement with evidences or equations. I assume ideal conditions where no air, or any object might contribute in friction losses. I will be so grateful if someone studies the following equations carefully and confirms whether or not possible.
One example is an oscillating ball vertically or a repelled magnet that is released from the ground to become free in a vacuum at a specific height. I'm afraid I'm not that confident of the mathematical model to be used because I lack for advanced mechanics. I tried using simple equations with the following assumptions:
1- Initial circular velocity of the floating body must be the same of that derived from angular velocity when the body was still on the ground. This is due to the conservation of energy that was only Kinetic.
2- No friction of any means exist.
3- Gravity variation with height is negligible.
According to the previous assumptions, my equation went this way:
If h is varying with time this will lead to a differential equation or can be approximated by converting h into an average value (hav = 2/3*hmax) and so the previous equation can be used as follows:
And the time required to cause a full rotation slip will be when
and so:
In terms of day time, T it will be:
and finally can be simplified to:
or more approximated,
Where T is the normal day = 24*3600 second.
--
Email4mobile (
talk)
19:41, 6 May 2009 (UTC)
I don't think it is related to coriolis effect. To make my question more clear; assume you're bouncing repeatedly at the Equator, normal to the Surface and forget about the latitude now. If we try to average your jumps (average potential energy) and returns to the ground; there results a fixed point above the ground where you're initiating your jumps by let's say height H. because your initial speed at the equator was the same rotational speed for the Earth it is supposed to be constant with height and hence, the angular velocity must be less at H which will cause a lag or offset proportional with time. This time may be several tenths of thousands of years (if hav=0.3m then T will be around 58000 years)to complete lagging rotation. This is of course true only if my calculations and analysis was correct. -- Email4mobile ( talk) 21:18, 6 May 2009 (UTC)
It seems to be independent of coriolis and Foucault pendulum effects because as you can see from the last simplified equation; the lag time (by one rotation) is only a function of the vertical hop (h)! —Preceding unsigned comment added by Email4mobile ( talk • contribs) 08:52, 7 May 2009 (UTC)
This is partly scientific, partly sociological.
I was told many years ago by my chemistry teacher that the quickest and most efficient way of mixing a soluble solid (such as sugar) into a liquid (such as tea or coffee) is to stir it in a roughly circular motion, and that "jiggling" the spoon up and down, or even side to side, in the liquid is less efficient. That always rang true with me, and it seems logical. I always stir, never jiggle. Firstly, I want to know if what I was told is scientifically correct.
If so, what could explain the phenomenon that "jiggling" is something that, in my experience, is done more by men than by women, who prefer to stir. Men are supposed to be the logical/scientific ones, yet women seem to have the right approach here. If it has something to do with men not wanting to be seen doing something in a "feminine" way, that's probably for a different desk, but any comments would be appreciated. -- JackofOz ( talk) 21:46, 6 May 2009 (UTC)
An article on Gamasutra about a lawsuit mentions that Richard Garriott was in "quarantine" in Russia after his spaceflight. Quarantine? Really? Is this an accurate description? Do they really quarantine cosmonauts after a flight, and why? Tempshill ( talk) 22:02, 6 May 2009 (UTC)
My partner and I have a pet cockatiel named George, in a large cage. It's perfectly happy there, and it's outside the house. A few weeks ago, a hawk was attacking the cage and frightening George, so my partner decided to put her (yes, George is a girl, a fact we only discovered when she started laying eggs) into a smaller cage and bring her inside the house. It was near a window where she and other birds outside could see each other. One bird in particular, a magpie, started to tap on the window with its beak. This would happen maybe a dozen times in the space of a few minutes, usually in the morning. I'd eventually get sick of it, shoo the maggie away, and that would be the end of that. Until next morning. We decided the hawk problem was no longer an issue, so we've now returned George to her normal cage outside. But this damn magpie still taps on the window every morning, as if George is still inside the house, when she plainly isn't. When George was inside, once I'd shooed the magpie away, it wouldn't return till the next day. But now, when I shoo it away, it comes back after a few minutes and starts tapping again. This goes on for a few hours now, whereas before it was only a few minutes. I can't swear it's the same magpie every time, but it looks like it might be. What's going on here? Is the magpie remembering the time when George was inside the house, and not connecting the bird that's outside now with the bird that used to be inside - or is it doing something it might have done anyway? I sort of doubt the latter, because we have a lot of birds around the house, but this window-tapping never happened until George was brought inside. -- JackofOz ( talk) 22:42, 6 May 2009 (UTC)
Science desk | ||
---|---|---|
< May 5 | << Apr | May | Jun >> | May 7 > |
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. |
Since lifting an object increases it's energy, wouldn't it therefore increase it's mass? And wouldn't this in turn increase it's energy even further, making a cycle? Since energy is rest mass + kinetic+other forms of energy etc. Also: Should I be using it's or its in my first sentence? That one has always bugged me, since I am showing ownership of the property, but I'm not sure if ownership transfers over to pronouns. If they don't then the un-contracted form being it is, would not make sense in that sentence. —Preceding unsigned comment added by 141.218.35.51 ( talk) 00:47, 6 May 2009 (UTC)
Thanks for the quick response to my grammatical question, I knew it felt wrong. "when energy of any kind is added to a resting body, or to a system of bodies, the increase in the mass as seen by a single observer (or as seen from any given inertial frame) is equal to the energy added, divided by c2." This was taken from the energy-rest mass equivalence article here. Wouldn't this cause the lifted object to experience increased mass? —Preceding unsigned comment added by 141.218.35.51 ( talk) 01:19, 6 May 2009 (UTC)
So I don't really understand where the mass is contained, if it is the gravitational field, what is the form in which it takes? 141.218.35.51 ( talk) 03:45, 6 May 2009 (UTC)
With regard to the infinite cycle problem, you have to be careful about how you are changing the potential energy of the object in your thought experiment. If I am holding a book on earth, and you define the system to be me+the book+earth, there is no energy being added to the system when I raise the book higher off the ground, I'm simply converting the electromagnetic potential energy stored in my muscles into another form of energy. So in that example, the relativistic mass does not change. Adding energy to the system would mean transferring it from an outside source, for example hitting the planet with light from the sun, or redefining the system to only encompass the Earth + the book. Truthforitsownsake ( talk) 12:47, 6 May 2009 (UTC)
To expand on the prior topic: Suppose we start with two masses in space which are gravitationally attracted to each other. As they approach they each gain kinetic energy and loose potential energy (potential energy becoming negative). When they collide, they merge and the potential energy becomes heat which eventually radiates away. With that loss of energy is a loss of mass as observed from outside the system. Now, suppose I were to descend into their gravitational well and measure their mass from there. Would my measurements equal the sum of the original two masses? To put it another way, would my observations from within the gravity-well be different than those at a distance? I know general relativity predicts gravitational time dilation, but what else changes? (..in layman's terms please, sans any stress-energy tensors and the like.) -- Tcncv ( talk) 04:21, 6 May 2009 (UTC)
q1-if light bulbs are connected to other bulbs just like in a series circuit such as in Christmas lights,they get dimmer .why is that? q2-if light bulbs are connected to other bulbs just like in a parallel circuit such as in household wiring .they stay bright .why? q3-how long light bulb last ?what happens to light bulb when it gives it's last glimmer I HAVESEARCHED EVERYWHERE google ,wikipedia ,my textbooks but i couldn't find it —Preceding unsigned comment added by Srijan89 ( talk • contribs) 07:40, 6 May 2009 (UTC)
Recently, in the last week, there were two occurences of the presence of a noisy fly in my house. The first, was precisely five days ago where the presence of the fly was known to me for sometime. During the morning and afternoon, it appeared that the fly was attracted to food, like other flies. It was extremely noisy, large and slow, making it easy to kill. However, it was most difficult to determine its location, as often it would sit still unless disturbed. At night, I happened to notice the fly, flying around a light source; it seemed quite far away from my position. I walked along (in my house) with no notice of it, for at least 10-15 metres. Then, to my surprise, I found it idle on my neck. I could not see it and therefore could not determine the exact second when it landed there, but having placed my hand on my neck alarmed me. The fly, to this sudden movement, responded by making a loud buzzing noise - extremely loud to my ear considering that it was on my neck. Within an instance, I noticed it on the wall in front of me. It came a surprise to me that a fly could travel such great distance in so little time, when, in my experience, such flies had been easy to kill and recognizable by their lack of agility. I approached the fly, and within an instant, killed it.
The next time that the presence of such a fly was beknownst to me, was merely a few hours ago. It seemed that the fly was attracted to any light source, often flying near the windows through which the light of the sun shone. It was therefore easy for me to trap the fly behind some curtins. Upon doing this, I heard a great buzzing noise - although I was certain that this fly was actually a fly, rather than a bee. The fly seemed to fly at a low altitude, making it somewhat inconspicuous. In the end, however, I killed it, in the same manner as that of the previous incident.
Based on the previous observations (concisely: loud buzzing noise, slow to move but quick in flight, large, inconspicuous, attracted to light - all in comparison to the average fly), what is the exact species of this fly? Based on my understanding of flies, I would predict this fly to be either a deer fly or a horse fly. However, despite being on my neck for sometime, the fly did not bite me. On the other hand, the flies which I have described seem more aggressive compared to other flies. It also seems that the ratio between the presence of these flies in my house, to the presence of the average fly in my house, is about 1:1. Furthermore, rarely is there such a fly during the summer season. Does anyone have any specific ideas regarding the species to which this fly belongs and the exact name of this fly? Thankyou for any remarks, and apologies for the somewhat long and narrative-like question that I am asking. -- PS T 10:09, 6 May 2009 (UTC)
Sounds to me like 1 of the Calliphorid flies or "dumb house flies". They would naturally overwinter in the burrows of animals but your walls or basement seem fine to them. As they warm up, like all ectotherms, they become active. They are attracted to light then since it would mean the way out of the animals burrow. As to why they landed on you, well they do lay thier eggs on other bugs and even eartworms but i doubt they thought you were one of thier potential hosts. Likely just seeking warmth. The Buzzing is likely just a predator avoidance thing, annoying yes, but harmless and effective. Most adults are pollen feeders. I would leave a light on near the door then just scoop the little buggers outside in the a.m. to continue thier important work!
I know the above is unsourced but hey, you asked!!! 67.193.179.241 ( talk) 15:34, 6 May 2009 (UTC) Rana sylvatica
Hi. In the 7.62x39mm cartridge (for example) what does the 7.62 stand for? I thought it was the bullet diameter, but apparently it's not. Also, why do they use 2 measurements instead of 1, like 9mm or .45? And what is shown by those specifications (9mm etc)? Thanks in advance —Preceding unsigned comment added by 122.255.2.65 ( talk) 11:59, 6 May 2009 (UTC)
First sorry for the title that doesnt says anything, but english is not my first language and I hope that you will understand what I am trying to know.The question:Why does a Cell-phone when lying on a table and ringing(vibrating) move? The phone should represent an Inertial frame and should not move as long as no force from outside is acting on it or am I wrong? Please explain. Thank You. DST —Preceding unsigned comment added by DSTiamat ( talk • contribs) 12:51, 6 May 2009 (UTC)
"So, if the internal little weight moves quickly in one direction, the rest of the phone will move slightly in the other"-Does this not violate the conservation of momentum? I understand that THIS IS conservation of momentum but if u see the Phone as one sytem who suddenly begins moving?Or should it not be seen this way? Explain please —Preceding unsigned comment added by DSTiamat ( talk • contribs) 13:51, 6 May 2009 (UTC)
The comparation is not the best because a car INTERRACTS whit the road through the weels where the phone does not(vacuum etc), i think it has something to do whit the moving of its centre of mass as Tango said, the momentum in case of the car is clearly conserved ( car moves one way, earth other etc) —Preceding unsigned comment added by DSTiamat ( talk • contribs) 13:58, 6 May 2009 (UTC)
Thank you Gandalf and SteveBaker really clever guys they understood what I was actually asking.
TY, DST —Preceding unsigned comment added by DSTiamat ( talk • contribs) 15:59, 6 May 2009 (UTC)
The reason the phone doesn't end up where it started if the vibrator moves quickly in one direction and slowly back (slowlyback-QUICK-slowlyback-QUICK) is beecause the slow movements leave it STATIONARY because of friction. It's the same as a jar. if you're in a jar and hit a basketball against the glass again and again and again and again, you could slowly move in that direction. That's because when it gets back to you, you catch it slower, so that there is literally 0 movement of the glass jar (due to friction of the ground) but when you throw it against the glass the quicker movement is able to overcome friction so that you move 0.001 meters for example. Do it enough times and you end up moving in that direction. But what about in space? In space if you are strapped in the center of an object and you keep throwing a basketball at the same wall and catch it on it's rebound back to you, you will NOT budge. When you catch the basketball again strapped to the center, even if you're doing it MORE SLOWLY, there is no FRICTION that makes this "more slow" movement = 0.
In conclusion: it's quite simple: your cell phone moves because friction makes it so that a force that would normally result in slow movement in fact results in 0 movement. So whereas in a vacuum it would vibrate like this: sachay slowly to one side, quickly to the other, slowly to one side, quickly to the other (remaining in the same net location), on the table it does this: sachays quickly to one side, remains still, sachays quickly to one side, remains still, ending up moving in that direction. The "remains still" part is where the vibrator, in space, would be countering the movement it just made, as it moves back so it can make it again...
79.122.21.123 (
talk)
19:11, 6 May 2009 (UTC)
that's very long steve, could you summarize it in a sentence the way I did with m ine? 94.27.231.41 ( talk) 11:17, 7 May 2009 (UTC)
I've got a huge, hairy black spider in my kitchen with yellow and black triangle markings down its back. Anyone know what it is? Thx in advance -- Anonymous07921 ( talk) 13:41, 6 May 2009 (UTC)
Google " camel spider bite" and click on images....that guy's leg looks pretty messed up. -- Anonymous07921 ( talk) 18:58, 6 May 2009 (UTC)
I would suggest taking a picture with a digital camera; all though this portal is brilliant for just about everything i feel the best person to ask would be the old guy in your neighbourhood who has lived there all his life; he may smell a little funny and start droaning on about the war while forcing you to have a game of Dominoes for his wisdom; but he will no doubt be able to tell you what type of spider it is and if it is going to sink its fangs into your flesh!!!! Chromagnum ( talk) 05:21, 7 May 2009 (UTC)
Scientists have discovered many stars that have planets at great distance using things like stars wobbling from planet gravity or a bit of dimming from a planet "eclipsing" the star. At what range from our solar system, would our scientists be able to detect that our own solar system has planets using their current methods? 65.121.141.34 ( talk) 13:59, 6 May 2009 (UTC)
I would also imagine that it is going to depend on where you are relative to the solar plane? If you are looking down on the solar system, a planet would never move in front of the sun, making planets harder to detect and greatly reducing your range then if you are in line with that plane right? 65.121.141.34 ( talk) 15:08, 6 May 2009 (UTC)
Hi, Wikipedia
Nowadays I'm trying to figure out how a mass body behaves when changing its position normal to the earth surface and I hope you can help me in this topic and confirm the correct statement with evidences or equations. I assume ideal conditions where no air, or any object might contribute in friction losses. I will be so grateful if someone studies the following equations carefully and confirms whether or not possible.
One example is an oscillating ball vertically or a repelled magnet that is released from the ground to become free in a vacuum at a specific height. I'm afraid I'm not that confident of the mathematical model to be used because I lack for advanced mechanics. I tried using simple equations with the following assumptions:
1- Initial circular velocity of the floating body must be the same of that derived from angular velocity when the body was still on the ground. This is due to the conservation of energy that was only Kinetic.
2- No friction of any means exist.
3- Gravity variation with height is negligible.
According to the previous assumptions, my equation went this way:
If h is varying with time this will lead to a differential equation or can be approximated by converting h into an average value (hav = 2/3*hmax) and so the previous equation can be used as follows:
And the time required to cause a full rotation slip will be when
and so:
In terms of day time, T it will be:
and finally can be simplified to:
or more approximated,
Where T is the normal day = 24*3600 second.
--
Email4mobile (
talk)
19:41, 6 May 2009 (UTC)
I don't think it is related to coriolis effect. To make my question more clear; assume you're bouncing repeatedly at the Equator, normal to the Surface and forget about the latitude now. If we try to average your jumps (average potential energy) and returns to the ground; there results a fixed point above the ground where you're initiating your jumps by let's say height H. because your initial speed at the equator was the same rotational speed for the Earth it is supposed to be constant with height and hence, the angular velocity must be less at H which will cause a lag or offset proportional with time. This time may be several tenths of thousands of years (if hav=0.3m then T will be around 58000 years)to complete lagging rotation. This is of course true only if my calculations and analysis was correct. -- Email4mobile ( talk) 21:18, 6 May 2009 (UTC)
It seems to be independent of coriolis and Foucault pendulum effects because as you can see from the last simplified equation; the lag time (by one rotation) is only a function of the vertical hop (h)! —Preceding unsigned comment added by Email4mobile ( talk • contribs) 08:52, 7 May 2009 (UTC)
This is partly scientific, partly sociological.
I was told many years ago by my chemistry teacher that the quickest and most efficient way of mixing a soluble solid (such as sugar) into a liquid (such as tea or coffee) is to stir it in a roughly circular motion, and that "jiggling" the spoon up and down, or even side to side, in the liquid is less efficient. That always rang true with me, and it seems logical. I always stir, never jiggle. Firstly, I want to know if what I was told is scientifically correct.
If so, what could explain the phenomenon that "jiggling" is something that, in my experience, is done more by men than by women, who prefer to stir. Men are supposed to be the logical/scientific ones, yet women seem to have the right approach here. If it has something to do with men not wanting to be seen doing something in a "feminine" way, that's probably for a different desk, but any comments would be appreciated. -- JackofOz ( talk) 21:46, 6 May 2009 (UTC)
An article on Gamasutra about a lawsuit mentions that Richard Garriott was in "quarantine" in Russia after his spaceflight. Quarantine? Really? Is this an accurate description? Do they really quarantine cosmonauts after a flight, and why? Tempshill ( talk) 22:02, 6 May 2009 (UTC)
My partner and I have a pet cockatiel named George, in a large cage. It's perfectly happy there, and it's outside the house. A few weeks ago, a hawk was attacking the cage and frightening George, so my partner decided to put her (yes, George is a girl, a fact we only discovered when she started laying eggs) into a smaller cage and bring her inside the house. It was near a window where she and other birds outside could see each other. One bird in particular, a magpie, started to tap on the window with its beak. This would happen maybe a dozen times in the space of a few minutes, usually in the morning. I'd eventually get sick of it, shoo the maggie away, and that would be the end of that. Until next morning. We decided the hawk problem was no longer an issue, so we've now returned George to her normal cage outside. But this damn magpie still taps on the window every morning, as if George is still inside the house, when she plainly isn't. When George was inside, once I'd shooed the magpie away, it wouldn't return till the next day. But now, when I shoo it away, it comes back after a few minutes and starts tapping again. This goes on for a few hours now, whereas before it was only a few minutes. I can't swear it's the same magpie every time, but it looks like it might be. What's going on here? Is the magpie remembering the time when George was inside the house, and not connecting the bird that's outside now with the bird that used to be inside - or is it doing something it might have done anyway? I sort of doubt the latter, because we have a lot of birds around the house, but this window-tapping never happened until George was brought inside. -- JackofOz ( talk) 22:42, 6 May 2009 (UTC)