# Activity for Canina‭

Type On... Excerpt Status Date
Comment Post #287004 If the front car is braking, that mostly changes how quickly the forward motion is converted into friction, because the brakes are designed to induce friction and the weight of the car in front would then be resting on mostly static wheels. (ABS may or may not make a difference here.) There is als...
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19 days ago
Comment Post #287004 **I think a fair portion of the answer to this question depends heavily on the closing speed of the two cars.** For simplicity, spherical cow style, assume equal crumple zones fore and back that are equal on both identical cars. It then stands to reason that approximately half of the energy of the im...
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19 days ago
Edit Post #286695 Post edited:
typeset formulae as formulae, not images
3 months ago
Suggested Edit Post #286695 Suggested edit:
typeset formulae as formulae, not images
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helpful 3 months ago
Edit Post #286665 Initial revision 3 months ago
Answer A: What should this community's policy on "explain like I'm five" and similar statements be?
My opinion is that such qualifiers, especially when combined with very general questions about specialized subjects, are not helpful. Generally, the tone of the question will be indicative of the level of expertise of the person asking the question. For example, if a question asks about quantum ph...
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3 months ago
Edit Post #286664 Initial revision 3 months ago
Question What should this community's policy on "explain like I'm five" and similar statements be?
Several questions have been posted recently where the user asking the question points to an extremely limited knowledge of the relevant field by asking of others to "explain like I'm five" (years old). How does the community feel about such qualifiers on questions? What should a community policy o...
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3 months ago
Comment Post #286662 This is at least your [second](https://physics.codidact.com/posts/286644/history) post in the last week or so where you claim to have asked a professional, to not have been able to understand the professional's answer, and instead of asking that person for a simpler explanation, apparently walked awa...
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3 months ago
Comment Post #286404 Relativistic effects start showing up in earnest around perhaps 80-90 % of *c*, which works out to somewhere in the neighborhood of 250 Mm/s. (For *significant* time dilation effects, you're looking at more like 99% to 99.99% of *c*.) [Apparently](https://en.wikipedia.org/wiki/Helios_(spacecraft)), t...
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5 months ago
Comment Post #285628 @#8056 From a quick glance at the introduction to that article, it sounds like that would make a very good alternative answer.
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9 months ago
Edit Post #285628 Initial revision 9 months ago
Answer A: May it be that there are more than 8/9 planets in our solar system?
Scientists rarely rule anything out completely. That said, I expect it to be highly unlikely. Recall that Pluto was hypothesized in the late 1800s as the source of perturbations observed in the orbits of Uranus and Neptune. Our measurements of the orbits of even the outer planets are almost cer...
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9 months ago
Comment Post #285323 Not a physicist, so I might be completely wrong here, but for your rebuttal of $T=\frac{1}{2}m\ddot{r}^2$, consider: What *is* the kinetic energy of a massless particle? Does a massless particle *have* any kinetic energy?
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10 months ago
Edit Post #285324 Post edited:
'terminology' would seem to apply here, as the question is about the term "outdated" and what qualifies as such
10 months ago
Suggested Edit Post #285324 Suggested edit:
'terminology' would seem to apply here, as the question is about the term "outdated" and what qualifies as such
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helpful 10 months ago
Comment Post #283996 There are several proposed approaches for timekeeping on Mars, some of which seem more reasonable than others for a human colony. Wikipedia has a rather lengthy article on [timekeeping on Mars](https://en.wikipedia.org/wiki/Timekeeping_on_Mars), including a discussion of "sol" being used as a term fo...
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10 months ago
Comment Post #283996 You are correct in that leap seconds can be inserted at the end of the year. However, they can also be inserted in the middle of the Gregorian year. Per [Wikipedia](https://en.wikipedia.org/wiki/Leap_seconds#Insertion_of_leap_seconds), the latter most recently happened in 2015, followed by a year-end...
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10 months ago
Comment Post #285129 @#36363 If you want to know what term would be used to describe such a part of the universe, then why are you asking if such parts of the universe exist?
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10 months ago
Comment Post #284890 I think it is the part of the wheel assembly that attaches to the bottom of the actual carry-on bag. The two black flat parts to the right in the image (one of which is just barely visible) are probably the actual wheels. But I agree that it would have been far, far better to just specify what the pi...
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10 months ago
Comment Post #285129 (1) In the title, you talk about ability to support life, whereas in the question body, you talk of ability for super-Earths to form. This would seem to, at best, be based on an assumption that only Earth-like planets can possibly support life as we know it. I don't *know*, but that *seems* to me lik...
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10 months ago
Comment Post #284862 Wouldn't calculating the center of thrust for a set of engines also require knowledge of the origin of the thrust vector of each respective engine, in relation to the others? Suppose that you have 11 engines of exactly equal thrust, 10 clustered close together and one far away from the others; the ce...
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11 months ago
Edit Post #284448 Post edited:
about 1 year ago
Suggested Edit Post #284448 Suggested edit:

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Comment Post #284434 Is this about whether and how to do so *in general*, or is it about *how to do it with Mathjax* (or more generally, with LaTeX)?
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about 1 year ago
Edit Post #284432 Post edited:
about 1 year ago
Edit Post #284432 Post edited:
about 1 year ago
Edit Post #284432 Initial revision about 1 year ago
Answer A: What is Ether theory? (I think the book I read is misinterpreting Ether)
Modern physics has pretty much dismissed the concept of the ether. Any modern claim that something like the luminiferous aether exists would be up against mountains of experimental results indicating that it doesn't, and mountains of experimental results indicating that theories based on the very con...
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about 1 year ago
Comment Post #284426 > The author wrote /.../ "earth is revolving the sun. It isn't moving circularly but just like oval. So if we think that the earth is too far away from sun at point A and it's closer to sun at point B". So the light from sun should reach to the earth more faster at point B rather than point A. Which ...
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about 1 year ago
Suggested Edit Post #283397 Suggested edit:
no need to use Mathjax in the question title here
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declined about 1 year ago
Comment Post #283502 One thing I found somewhat interesting is that [Neptune's albedo](https://www.universetoday.com/21581/neptune/) (apparently >0.7 to 0.9) is about that same as [Earth's *would be*](https://www.earthobservatory.nasa.gov/images/84499/measuring-earths-albedo) if Earth was completely covered in ice. NASA ...
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about 1 year ago
Comment Post #283680 I, too, see no Abilities block in the profile pages for Mithrandir and Monica Cellio, but I do see it for you and myself (when logged out). Might it be because they are Staff?
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about 1 year ago
Edit Post #282190 Post edited:
about 1 year ago
Comment Post #283511 Also, I wasn't quite sure what you meant with your last paragraph (and especially the final parenthetical), so I largely left that one alone. For example, I don't know what you meant to say by "is it mattering for charge?". You might want to consider if that can be edited to clarify what you are aski...
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about 1 year ago
Comment Post #283511 @#53922 Nouns aren't written with an initial capital letter in English; however, proper names are. (With a few exceptions, such as names of units, which may or may not be capitalized; *for example,* *Newton* and *Sievert* are capitalized when used as the name of the unit, but *gram* and *second* are ...
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about 1 year ago
Edit Post #283511 Post edited:
copy-editing
about 1 year ago
Suggested Edit Post #283511 Suggested edit:
copy-editing
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Comment Post #283420 I don't know if this is it, but in calculating $F$, you have $\rho = 970$; but what unit is intended? Specifying density in mg/cm³ seems a somewhat odd choice.
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about 1 year ago
Edit Post #283386 Post edited:
Typeset equation using inline Mathjax instead of as image, plus minor formatting and copy-editing
about 1 year ago
Suggested Edit Post #283386 Suggested edit:
Typeset equation using inline Mathjax instead of as image, plus minor formatting and copy-editing
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Edit Post #282190 Initial revision over 1 year ago
Answer A: Natural ways to acquire gravity for a colony on earth's moon
Since you specify in the title that you're asking about ways to "aquire gravity", I'm going to assume that by "natural gravity" in the question body you refer to a gravitational acceleration substantially closer to Earth's 9.8 m/s2 than Earth's Moon's 1.6 m/s2. (Neither value is any more "natural" th...
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over 1 year ago
Comment Post #281840 Also, I have no idea how that extension might work (I don't use Chrome myself), but there's a myriad reasons why it wouldn't give actual measurements relative to some reference level, not least of which being that there's already a handful of adjustments that can be made before the sound even reaches...
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over 1 year ago
Comment Post #281840 Any decibel (or other fraction) value will be in relationship to something; that "something" is the reference value or level. For example, dBA SPL (which you'd *probably* see in relation to sound pressure levels) is not at all the same thing as dBm (decibel relative to 1 mW) or dBi (decibel relative ...
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over 1 year ago
Comment Post #281840 Please keep in mind that decibel (which is equal to 1/10 Bel) is just a unit of ratio. A ratio alone tells you nothing about the magnitude of the value if you don't specify your reference level.
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over 1 year ago
Comment Post #280853 I'm not sure how this is a physics question. The matter of perception of the passage of time seems to me to be more along the lines of psychology than physics, as the passage of time itself doesn't change, nor the rate of change on a clock; only your perception of the passage of time might change.
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over 1 year ago