Gravitational force means"the force experienced between two heavenly bodies".A body falls on any planet due to gravitational force.But smaller planets are not attracted by larger planets or stars(sun) due to this force. What is the reason for this?
Why doesn't the Moon fall onto the Earth? For that matter, why doesn't anything rotating a larger body ever fall onto the larger body?
When speaking precisely or technically, one would say that "Homo erectus and homo sapiens are two species of hominid" rather than "Homo erectus and homo sapiens are two species of hominids." The hominid here should be singular because we are speaking about instances of a single class ("class" being used here in its broader sense, not in the sense of taxonomic grouping).  Now let's consider more common parallel constructions replacing the word species with other words.      Tide and Wisk are two brands of detergent.       Tide and Wisk are two brands of detergents.      Cats and dogs are two types of pet you can buy at Pets-R-Us.       Cats and dogs are two types of pets you can buy at Pets-R-Us.   I feel that using the singular noun to specify the class is more grammatically correct, but sounds stilted in conversation. Almost everyone I hear making these constructions uses the plural form. What are your thoughts about singular vs. plural here?  Edit  Here's a more extreme example that may help clarify the issue. Consider the following sentence:     It was my first attempt at calming an angry crowd, and I just        stood there while people were hurling all kinds of insults at me.   Here I think the singular insult sounds strange, if not downright wrong.  Further Edit  I just noticed in A Treasury for Word Lovers (Morton S. Freeman, 1983) a section entitled "Types of Errors." This is a book about (American) English usage by an English professor and editor, which purports to be a "practical guide for serious writers and readers." I wish I could say this discovery satisfies the question, but in fact I now feel somewhat farther from the truth, if there is any single "truth" in this matter. But at least I don't have to worry about being wrong when using the plural form of the class in these constructions. Is "life" a countable noun in English? I am a learner of English. Sometimes I see an article (a and the) before the noun (life) but sometimes I also see the noun without any article. So I am confused when should I use an article before the noun and when I should not. Please check the examples and let me know are they correct?     Examples:      His life is an awesome life.      I want to get a beautiful life.      I like the life he lived. Change the folder that Windows Explorer starts at In Windows7, when you open the Windows Explorer using the pinned Windows Explorer button on taskbar, it opens WE and points it to My Documents folder.  Is there a way to change this so it doesn't open My Documents, but rather "Computer" just as Windows+E keyboard shortcut does? How to find string position within another string in C recursively? Powershell Parameters self referential struct definition? How to remove a filter that is an anonymous object? In my functions.php file I would like to remove the below filter, but I'm not sure how to do it since it's in a class. What should remove_filter() look like?  add_filter('comments_array',array( &amp;$this, 'FbComments' ));   It's on line 88 . There appears to be a giant security vulnerability with Android that seems to basically affect all phones.  wrote:  The vast majority of Android phones can be hacked by sending them a specially crafted multimedia message (MMS), a security researcher [Joshua Drake] has found. ... Drake found multiple vulnerabilities in a core Android component called Stagefright that’s used to process, play and record multimedia files. Some of the flaws allow for remote code execution and can be triggered when receiving an MMS message, downloading a specially crafted video file through the browser or opening a Web page with embedded multimedia content. ... The MMS attack vector is the scariest of all because it doesn’t require any interaction from the user; the phone just needs to receive a malicious message. For example, the attacker could send the malicious MMS when the victim is sleeping and the phone’s ringer is silenced, Drake said. After exploitation the message can be deleted, so the victim will never even know that his phone was hacked, he said.  What can a regular user do to mitigate the issue? Disable Google Hangouts? I have recently begun self-studying Number Theory, and am working on proving:     Show that every integer $n&gt;0$ can be uniquely written as $$n = \sum_{i=0}^mc_i3^i$$ where $c_i \in \{ -1,0,1\}$ and $c_m \neq 0$.   I believe I have already shown the existence portion of this proof correctly, and now I am looking for some hints on the uniqueness part. So far what I have tried is:     Suppose for the sake of contradiction that there is an alternate representation of $n$ besides $n = \sum_{i=0}^mc_i3^i$, say $n = \sum_{i=0}^pb_i3^i$ where we still have $b_p \neq 0$ and $b_i \in \{-1,0,1\}$.    At this point I felt that I first need to establish that $m=p$, and second show $c_i=b_i$ for each $i \in \{1,2,\dots,  m\}$. To show the former, I left off in my proof by contradiction with      Without loss of generality suppose $p&gt;m$. We know there is an integer $q$ such that $m+q=p$. We have two ways of writing $n$, which means $$ \sum_{i=0}^pb_i3^i-\sum_{i=0}^mc_i3^i=0 \\ \implies \left(\sum_{i=0}^mb_i3^i+\sum_{i=m+1}^{m+q}b_i3^i\right)-\sum_{i=0}^mc_i3^i=0 \\ \implies \sum_{i=0}^m(b_i-c_i)3^i+\sum_{i=m+1}^{m+q}b_i3^i=0 \\ \implies \sum_{i=m+1}^{m+q}b_i3^i=\sum_{i=0}^m(c_i-b_i)3^i$$   At this point I am stuck. If anyone has any hints to help me find the contradiction or feel that there is a better way to establish uniqueness, please let me know! I launch a batch which call a lot of scheduled job. But I reach the governor limit :     Maximum number of Apex classes scheduled concurrently : 100   I'm wondering what happens when this limit is reached. The next scheduled jobs are waiting the number of scheduled jobs is lower than 100 for being executed or are they all cancelled ?  And is there to way to manage the number of scheduled jobs to avoir reaching this limit ? For example wait before schedule a new job if we are near the limit. What do you call someone who always puts blame on others? How to create a list template by using CSOM? What is the default bibliography package and backend in LaTeX? According to , biblatex and natbib are packages while biber and bibtex are backends. If I don't specify either any package or any backend, it still compiles fine. Which package and backend combination is being used in this case?  demo.tex  \documentclass{article} \begin{document}  \nocite{*} \bibliographystyle{ieeetr} \bibliography{pub}  \end{document}   pub.bib  @article{janssen1996evaluation,     title={Evaluation of the DNA fingerprinting method AFLP as a new tool in bacterial taxonomy},     author={Janssen, Paul and Coopman, Renata and Huys, Geert and Swings, Jean and Bleeker, Marjo and Vos, Pieter and Zabeau, Marc and Kersters, Karel},     journal={Microbiology},     volume={142},     number={7},     pages={1881--1893},     year={1996},     publisher={Soc General Microbiol} }  @article{vos1995aflp,     title={AFLP: a new technique for DNA fingerprinting},     author={Vos, Pieter and Hogers, Rene and Bleeker, Marjo and Reijans, Martin and Van de Lee, Theo and Hornes, Miranda and Friters, Adrie and Pot, Jerina and Paleman, Johan and Kuiper, Martin and others},     journal={Nucleic acids research},     volume={23},     number={21},     pages={4407--4414},     year={1995},     publisher={Oxford Univ Press} } Does Power Word Kill kill druids in wild-shape? Why is my fire simulation so light? I have been struggling to get a match tip to actually look like it's on fire and no matter what material shaders I try, I can't seem to achieve what everyone else does, I can in other scenes, just not this one. :( I saw several bugs and error messages when I was looking by chance into the tool called "logs".  Being a newbie in Ubuntu I have no idea how to deal with these bugs, where to report them or how to fix them.  Any help to guide me here?  The bug I have (which is listed under important) reads:  [Firmware Bug]: TSC_DEADLINE disabled due to Errata; please update microcode to version: 0x52 (or later) What are the correct version numbers for C#? Does anyone know of a simple Image Editor, with functionality comparable to ,  for Ubuntu?  I've always found GIMP to be overkill and too complicated for what I want to do. I've got about a billion rows of data in a table with a name and an integer in the range 1-288.  For a given name, every int is unique, and not every possible integer in the range is present--so there are gaps.  This query generates an example case:  --what I have: SELECT * FROM ( VALUES ('foo', 2),               ('foo', 3),               ('foo', 4),               ('foo', 10),               ('foo', 11),               ('foo', 13),               ('bar', 1),               ('bar', 2),               ('bar', 3)      ) AS baz ("name", "int")   I'd like to generate a lookup table with a row for each name and sequence of contiguous integers.  Each such row would contain:  name   --  the value of the name column start  --  the first integer in the contiguous sequence end    --  the final value in the contiguous sequence span   --  end - start + 1  This query generates example output for the above example:  --what I need: SELECT *  FROM ( VALUES ('foo', 2, 4, 3),               ('foo', 10, 11, 2),               ('foo', 13, 13, 1),               ('bar', 1, 3, 3)      ) AS contiguous_ranges ("name", "start", "end", span)   Because I have so many rows, more efficient is better.  That said, I only have to run this query once, so it isn't an absolute requirement.  Thanks in advance!  Edit:  I should add that PL/pgSQL solutions are welcome (please explain any Fancy Tricks--I'm still new to PL/pgSQL). For which values of $\alpha$ and $\beta$ does the integral $\int\limits_2^{\infty}\frac{dx}{x^{\alpha}\ln^{\beta}x}$ converge?