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February 27 Information
Bulletin of the Seismological Society of America in online libraries?
I'm trying to make the cited sources in
White Wolf Fault as accessible to readers as possible but I haven't been able to find this journal in the Internet Archive, JSTOR or Wiley. HathiTrust only has the issues from 1911 to 1926. The Seismological Society of America's website has has the issues cited, but it requires library or institutional access. If there are other journal repositories in our Library that have it, I've missed them. I'm stumped. If someone can help out, future readers will be better off...
I do not at all mind having to hunt down the article in the proper repository (keeps me from getting lazy, lol). Just point me in the right direction and off I'll go!
Oona Wikiwalker (
talk)
07:19, 27 February 2024 (UTC)reply
The cited articles are also available online for a (hefty) fee at GeoScienceWorld; see
here and
here. The fee imposed suggests that the publisher enforces its copyright. --
Lambiam11:38, 27 February 2024 (UTC)reply
But Library access is within copyright restrictions because they pay for access for their patrons. That's what I'm inquiring after; did I miss a collection within our library that contains this journal?
I've checked the Wikipedia Library and it doesn't provide access. I have added the doi and bibcode to the cite to make it a bit easier for readers to click to the journal.
Mike Turnbull (
talk)
16:48, 28 February 2024 (UTC)reply
The version with c2 is formally correct. Another matter is whether that should be in the lede of the article (and who is "some authors"?). I don't think I've ever seen that convention — whenever I've seen it was due to setting , in which case . --
Wrongfilter (
talk)
18:13, 27 February 2024 (UTC)reply
I admit I'm quite surprised. The four momentum is (p0, p1, p2, p3), traditionally written also as (E/c, px, py, pz), hence: p0 = E/c. On the other hand, both sides of the current expression (in the lede): p0 = E/c2 don't have the same units, so how can it be correct?
HOTmag (
talk)
18:29, 27 February 2024 (UTC)reply
You are allowed to avoid answering my last question, which has nothing to do with the article. Actually, regardless of the article, I was quite curious to know whether you also considered the third statement p0 = E/c (which had been my correction before it was reverted): as "weird", while I assumed you accepted the two statements it followed, and that's why I asked you my last question, regardless of the article. But again, nobody forces you to answer my last question.
HOTmag (
talk)
19:44, 27 February 2024 (UTC)reply
So (back to article), my correction p0 = E/c in the article was right, and it didn't have to be reverted to p0 = E/c2. That's what I wanted to know from the very beginning: whether the user who reverted my correction was wrong (as I thought).
HOTmag (
talk)
22:26, 27 February 2024 (UTC)reply
No you were wrong in that context. That bit has been removed now from the article because what was there isn't common and as shown here will just cause confusion. It is best to have all the elements using the same units.
NadVolum (
talk)
23:25, 27 February 2024 (UTC)reply
I haven't asked about whether the context justified mentioning this formula there, nor about why the whole formula was eventually removed. I've only asked about whether, my replacing the original formulation p0 = E/c2 by the correct formula p0 = E/c, had been a better version than the original version p0 = E/c2. In other words, I've wanted to know if the user who reverted my correction p0 = E/c back to the original version p0 = E/c2 made the article worse. I think they did, and I've wanted to get your opinion about what I think. All of that is quite clear in my first post, that had actually been posted before the whole formula was eventually removed.
HOTmag (
talk)
08:07, 28 February 2024 (UTC)reply
The original statement was a conditional, with an "if... then..." structure. The formula that you changed was in the "then..." part, and was correct under the condition stated in the "if..." part. By changing the "then..." part without taking into account the "if..." part, you introduced an error, and the other user was right in reverting your edit. --
Wrongfilter (
talk)
08:38, 28 February 2024 (UTC)reply
I got it now. Thank you. I understand now that the original "then" part (before I changed it) would be correct assuming that the "if" part were correct. However, the "if" part really introduces a definition I've never come across, and should be omitted.
HOTmag (
talk)
09:52, 28 February 2024 (UTC)reply
Parachutes and terminal velocity
Hi, I'm currently doing a lab using a small model parachute. As I currently understand it, the
terminal velocity can be calculated by equating the weight of the object to the drag force, given by the
drag equation. My question is, how can I use this terminal velocity to estimate the time it would take an object to fall a set distance? Do I assume the object starts out at terminal velocity? Do I use a SUVAT equation? Thanks!
ARandomName123 (
talk)Ping me!23:05, 27 February 2024 (UTC)reply
Take the height of the fall, divide by the terminal velocity. That gives you a rough answer. So if the falling object gets close to terminal velocity after just a short fraction of the fall (for a human with a parachute, around 50 metres) and the fall is short compared to the scale height of the atmosphere (around 7 kilometres on Earth; else the changing density changes the terminal velocity) and you don't care too much about the second digit of your answer, this may be good enough. Otherwise, you have to integrate the equations of motion.
PiusImpavidus (
talk)
11:18, 28 February 2024 (UTC)reply
In the following, we only consider the motion of an idealized point particle along a vertical line. We use the variables for time, for the particle's position above , for its velocity and for its acceleration. Furthermore, stands for its mass and for the acceleration of gravity.
The force exerted on the particle is the sum of the forces due to drag and to gravity:
in which whose form given by the
drag equation, contains a yet unknown constant Its value may be determined if the terminal velocity is known, as follows. Terminal velocity is the limit velocity, approximated arbitrarily closely as the acceleration tends to which means (since then tends to 0) that the upward drag force cancels the downward gravitational force, or It follows that so now we have
This differential equation, combined with the condition that at time the moment of release, is solved by:
Integrating again, with the condition that at time the particle is released from a given height results in:
Solving for gives the time it takes the particle to reach ground level:
in which stands for the
inverse hyperbolic cosine. Asymptotically, as tends to infinity, this is equal to
Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is a
transcluded archive page. While you can leave answers for any questions shown below, please ask new questions on one of the
current reference desk pages.
February 27 Information
Bulletin of the Seismological Society of America in online libraries?
I'm trying to make the cited sources in
White Wolf Fault as accessible to readers as possible but I haven't been able to find this journal in the Internet Archive, JSTOR or Wiley. HathiTrust only has the issues from 1911 to 1926. The Seismological Society of America's website has has the issues cited, but it requires library or institutional access. If there are other journal repositories in our Library that have it, I've missed them. I'm stumped. If someone can help out, future readers will be better off...
I do not at all mind having to hunt down the article in the proper repository (keeps me from getting lazy, lol). Just point me in the right direction and off I'll go!
Oona Wikiwalker (
talk)
07:19, 27 February 2024 (UTC)reply
The cited articles are also available online for a (hefty) fee at GeoScienceWorld; see
here and
here. The fee imposed suggests that the publisher enforces its copyright. --
Lambiam11:38, 27 February 2024 (UTC)reply
But Library access is within copyright restrictions because they pay for access for their patrons. That's what I'm inquiring after; did I miss a collection within our library that contains this journal?
I've checked the Wikipedia Library and it doesn't provide access. I have added the doi and bibcode to the cite to make it a bit easier for readers to click to the journal.
Mike Turnbull (
talk)
16:48, 28 February 2024 (UTC)reply
The version with c2 is formally correct. Another matter is whether that should be in the lede of the article (and who is "some authors"?). I don't think I've ever seen that convention — whenever I've seen it was due to setting , in which case . --
Wrongfilter (
talk)
18:13, 27 February 2024 (UTC)reply
I admit I'm quite surprised. The four momentum is (p0, p1, p2, p3), traditionally written also as (E/c, px, py, pz), hence: p0 = E/c. On the other hand, both sides of the current expression (in the lede): p0 = E/c2 don't have the same units, so how can it be correct?
HOTmag (
talk)
18:29, 27 February 2024 (UTC)reply
You are allowed to avoid answering my last question, which has nothing to do with the article. Actually, regardless of the article, I was quite curious to know whether you also considered the third statement p0 = E/c (which had been my correction before it was reverted): as "weird", while I assumed you accepted the two statements it followed, and that's why I asked you my last question, regardless of the article. But again, nobody forces you to answer my last question.
HOTmag (
talk)
19:44, 27 February 2024 (UTC)reply
So (back to article), my correction p0 = E/c in the article was right, and it didn't have to be reverted to p0 = E/c2. That's what I wanted to know from the very beginning: whether the user who reverted my correction was wrong (as I thought).
HOTmag (
talk)
22:26, 27 February 2024 (UTC)reply
No you were wrong in that context. That bit has been removed now from the article because what was there isn't common and as shown here will just cause confusion. It is best to have all the elements using the same units.
NadVolum (
talk)
23:25, 27 February 2024 (UTC)reply
I haven't asked about whether the context justified mentioning this formula there, nor about why the whole formula was eventually removed. I've only asked about whether, my replacing the original formulation p0 = E/c2 by the correct formula p0 = E/c, had been a better version than the original version p0 = E/c2. In other words, I've wanted to know if the user who reverted my correction p0 = E/c back to the original version p0 = E/c2 made the article worse. I think they did, and I've wanted to get your opinion about what I think. All of that is quite clear in my first post, that had actually been posted before the whole formula was eventually removed.
HOTmag (
talk)
08:07, 28 February 2024 (UTC)reply
The original statement was a conditional, with an "if... then..." structure. The formula that you changed was in the "then..." part, and was correct under the condition stated in the "if..." part. By changing the "then..." part without taking into account the "if..." part, you introduced an error, and the other user was right in reverting your edit. --
Wrongfilter (
talk)
08:38, 28 February 2024 (UTC)reply
I got it now. Thank you. I understand now that the original "then" part (before I changed it) would be correct assuming that the "if" part were correct. However, the "if" part really introduces a definition I've never come across, and should be omitted.
HOTmag (
talk)
09:52, 28 February 2024 (UTC)reply
Parachutes and terminal velocity
Hi, I'm currently doing a lab using a small model parachute. As I currently understand it, the
terminal velocity can be calculated by equating the weight of the object to the drag force, given by the
drag equation. My question is, how can I use this terminal velocity to estimate the time it would take an object to fall a set distance? Do I assume the object starts out at terminal velocity? Do I use a SUVAT equation? Thanks!
ARandomName123 (
talk)Ping me!23:05, 27 February 2024 (UTC)reply
Take the height of the fall, divide by the terminal velocity. That gives you a rough answer. So if the falling object gets close to terminal velocity after just a short fraction of the fall (for a human with a parachute, around 50 metres) and the fall is short compared to the scale height of the atmosphere (around 7 kilometres on Earth; else the changing density changes the terminal velocity) and you don't care too much about the second digit of your answer, this may be good enough. Otherwise, you have to integrate the equations of motion.
PiusImpavidus (
talk)
11:18, 28 February 2024 (UTC)reply
In the following, we only consider the motion of an idealized point particle along a vertical line. We use the variables for time, for the particle's position above , for its velocity and for its acceleration. Furthermore, stands for its mass and for the acceleration of gravity.
The force exerted on the particle is the sum of the forces due to drag and to gravity:
in which whose form given by the
drag equation, contains a yet unknown constant Its value may be determined if the terminal velocity is known, as follows. Terminal velocity is the limit velocity, approximated arbitrarily closely as the acceleration tends to which means (since then tends to 0) that the upward drag force cancels the downward gravitational force, or It follows that so now we have
This differential equation, combined with the condition that at time the moment of release, is solved by:
Integrating again, with the condition that at time the particle is released from a given height results in:
Solving for gives the time it takes the particle to reach ground level:
in which stands for the
inverse hyperbolic cosine. Asymptotically, as tends to infinity, this is equal to