Interesting Definition and 790 Threads

hey, I'm having a bit trouble solving this physics question! :mad: so if anyone can help me, here it is: A stone is thrown up past a window. The stone requires 0.20s to completely pass by the 1.4m tall window. How high above the window did the stone go? I'm aware that the average velocity...

26/65 = 2/5 (cross out the sixes) 16/64 = 1/4 (again cross out the sixes) are there anymore *interesting* numbers like this? by interesting i mean that its not 11/11, since you can obviously cross out the 1's and get 1/1. the numbers have to be different also, are there any 3 digit...

I finished my undergraduate curriculum in physics and I'm out of school, working from home. School doesn't tell me what to do anymore.. I'm looking for an interesting problem I can work on, either a problem that could be solvable mathematically or some hands-on-experiments that I can do at home...

An interesting integral appeared on a test that I took today. I had no idea how to solve it, and was wondering if any of you all could possibly help me \int_{0}^{1} \frac{1}{x}-floor(\frac{1}{x}) we first had to draw the graph from 0 to 1, (which has a max of 1, a min of 0 (at 1/n for...

Don't know how long these will be active, but they are interesting: Lecture 16 - Down To Earth III: Earth Structure http://www.astro.lsa.umich.edu/users/cowley/lecture16/ Lecture 17 - Earth and Its Nearest Cosmic Neighbor, The Moon http://www.astro.lsa.umich.edu/users/cowley/lecture17/...

How can it be proved that Rnl(r) has (n-l-1) zeros (not counting those at r-0 and r= infinity? I tried doing this inductively but found it hard to get anywhere since the equations for Rnl(r) aren't too pretty. For instance, Rnl(r)=Anlunl where Anl= sqrt((n-l-1)!/(2n((n+l)!)^3) this last...

I put icecream in my microwave for about 20 seconds. When i take it out i notice that it's softest in the centre. However, when i defrost a loaf of bread it's always softest on the outside and still cold in the centre. Why is this, and if you don't believe me try it!

Pat shoots an arrow vertically upward with an initial speed of 25 m/s. When it is exactly halfway to the peak of its flight, he shoots a second arrow vertically upward from the same spot. They collide just as the first arrow reaches its highest point. (A) What is the Launch Speed of the...

First of all note this is NOT HOMEWORK This is an interesting geometry problem my old statistics and discrete math teacher gave to me, i solved it, however i just wanted to give it out... very tough problem (at least for me, probably easy for most poeple here) You have a triangle... the...

I'm a grade 12 student and have been given the task of teaching our algebra and geometry class for a day :smile: . There are absolutely no restrictions on what I can teach about. It does not in any way have to be related to algebra or geometry, just mathematics in general. What I really need is...

starting with 2,0,0,5 form the sequence 2,0,0,5,7,2,4,8,1 ... where each successive digit is the unit digit of the sum of the previous 4 ( 2+0+0+5=7, 0+0+5+7=12 , write 2, .. etc.) does the sequence 4,0,5,3 ever appear ? prove your answer i have been trying to see some sort of pattern...

Assuming o(1) is +, o(2) is *, o(3) is ^, etc how would you go about solving an equation such as: y = 3 o(x) 4 (where y is a given number and you must find x) I can't imagine how you would isolate x, you'd need an inverse o() of sorts. ie: x = o'(3, 4, y) (Hey, a 4d graph needed to...

I had a interesting dream two nights ago, I will explain it. A woman with "Angel" in her name told me the name "Deivion", after this I saw a another woman's name with an "Angel" design by it (as you would see on a card or such). Now after this a man approached me with urgentcy crying...

What about the quantum mechanics captures your interest?

Hurklyl, you are the resident mathematician, you might check this out carefully. Relativity is really a very complex issue seldom examined in detail by anyone. For example, I suspect almost everyone here who has ever taken a course in relativity has seen the exposition on looking at the back...

I need some help getting started on this one: Sound waves of frequency 582 Hz enter a window 1.3m wide. The window is in the exact center of one wall of a theater 24m by 12m. The window is 12m from the opposite wall, along which is a row of seats occupied by people. The theater is...

Hi, my teacher gave this problem and he said that it has a very "pretty" answer. You have two equal masses, each mass is called M that are touching each other. There is a block with mass m on top of the first mass M. This block is a distance H above the ground. When the block is released...

I just read the cover article in the most recent issue of Scientific American about viruses. The article was pretty interesting; it gives a short overview of the basics of what viruses do and how they do it and talks about their role in evolutionary history of organisms. The article also...

Here are a few questions that I have built up. If someone knows the awsner to some of them, I would greatly appreteate your help. 1.If a "body" were to exceed c, then time would go in reverse for that body of motion, not time around them, right? For instance, let A travel faster than c...

http://www.cartoline.it/pics/_zoom_flash.htm?immagine=scherzi_150404_01.swf > > 1. CLICK ON THE LINK > 2. PUT THE COIN IN THE VENDING MACHINE > 3. CHOOSE YOUR DRINK > 4. CLICK ON THE CUP WHEN IT IS READY > 5. CLICK ON "APRI" **** Don't forget to click on APRI

I'm about to do this project in which we will prepare and perform an experiment and then later tell the class about it. All this in about a week. I'm now trying to come up with some interesting experiment to do during this time. I'd really like some help on the subject. I'm looking for an...

http://www.sciencemusings.com/blog/2004/11/evidence-based-reality.html Follow the links for further discussion, like this one... http://www.boston.com/news/globe/editorial_opinion/oped/articles/2004/10/31/walking_the_walk_on_family_values/

This is a problem needed for a project...i have no clue what to do... two rods are lying parallel, with a third lying perpindicular across them, like a football goal post. how does one relate coefficient of static and kinetic friction between them, if only distance is measurable. This...

hi, I am looking for any suggestions as to an interesting and relatively deep (but not too deep) topic to do a presentation on. This can be anything to do with physics e.g the collapse of the tacoma narrows bridge, particle physics, time travel, the doppler effect or any physics phenomena. Any...

From the NCSE Oct 15 e-newsletter. I'm not trying to promote ID here, but it sure is refreshing to hear a voice from that arena finally say "hey, shouldn't we be using science to prove our case?"

I'm not very knowledgeable of physics as my main focus is computer technology. However, I purchased a Magnetix set from a local store a few days ago because I remembered these kinds of sets when I was a kid. With this 20 piece set I created a hexagon and had one remaining ball left over. I...

Greetings ! Maybe I'm just too tired and missing something, but this strange thing occured to me: a^n + b^n = c^n ln( a^n + b^n ) = n * ln ( c ) a^n + b^n =/= e^n * c example: a = 3; b = 4; c = 5; n = 2; 25 =/= e^2 * 5 Live long and prosper.

Hi everyone :smile: ! I have been looking for some data about something fun or interesting. I've only been able to find boring things like the results to a coin toss. Does anyone know of a website that has real data on something fun or interesting? ~Thanks

My linear algebra professor likes to use theorems he expects us to prove later in his proofs of theorems in class. Well it's not like that because it makes sense but they're usually more of side notes. Today he asked us to prove this: Given A and B are 2 by 2 matrices over the field R...

While poking around and reviewing some the old CIA files at the FOIA [Freedom of Information Act] reading room, I noticed a rather unusual, forty eight page document dated Aug, 1945, that discusses Japaneses espionage and secret operatives, Chinese complicity, and is titled "SHANGHAI -...

I've had this article for quite some time, and I find it to reflect greatly on the current political situation in America. The article was written in 1938 by Garet Garrett http://www.rooseveltmyth.com/docs/The_Revolution_Was.html Take some time, read it, and let me know what you think...

Are there two matrices A and B such that A*B is the zero matrix but B*A is not? I'm leaning toward no.. I'm composing my solution right now. Bah the only thing I can come up with is that if any row of A can be treated as a vector and any column of row B can be treated as a vector, for...

I have a trouble with this problem: Suppose you have a particle with mass 30Kg, this particle is in influence of a force F that acts along the x-axis and F=6+4x-3(x^2) and at x=0 the particle has 0m/s speed. Find the total work made by F between x=0 and x=3, then find the power given to the...

Interesting to see the detail put into campaigns... In this case, the debates... You know, I always hear the statement of the tallest candidate winning ever since debates were televised (don't even know if that is true), but this little story really shows that every angle is being covered...

here's the problem: You are given a seven digit number. Prove that you can cross off some of the numbers at the beginning or the end and you'll be left with a number that is divisible by 7. For example: 1434945 Cross off the first three and last two to get 49. I have a proof of...

Ok. This one is giving me some trouble: A space person is motionless a distance of 500.0 m from the safety of the space craft. The person has exactly 11.32 minutes of air left, and the person's mass is 103.2 kg including the equipment. The person throws a phaser (for all you Trekkies) at a...

Longbets.org is taking bold predictions and allowing people to place bets (long term only!) about our futures in sciences and sociology. The bets go to charities and other non-profits, when resolved. Here is one that is of particular interest to this group. http://www.longbets.org/12...

This was a very interesting article on sleep http://health.yahoo.com/health/centers/sleep_disorders/_101.html

hello people, my name is tom schulte and I am from germany. I have some interesting links for you. It would be nice if you would look at them www.intalek.com www.cheniere.org www.stardrivedevice.com www.disclosureproject.org these websites tell you about some energie and propulsion...

hello people, my name is tom schulte and I am from germany. I have some interesting links for you. It would be nice if you would look at them www.intalek.com www.cheniere.org www.stardrivedevice.com www.disclosureproject.org these websites tell you about some energie and propulsion...

I am reading an old book about Carbon Dating and it is really boring, I dstill havenot found out there is anything interesting for me to keep going with time continuum, continuum continuum, again and again...So would you please introduce me some (old or new) interesting books on the topic for me...

Just an interesting observation...there's no Phosphate in amino acids...why?

I'm heading to Vancouver next week and I'm wondering if any of you have any suggestions as to what to see and where to go ... I'm actually there for 3 whole weeks, so I will have quite a lot of time to spend. Please try to keep off the likes of Art Museums coz I get dead bored :zzz: in such...

http://www.blessa.com/64-equals-65.gif

Imagine you are spinning on a top. You naturally go to the edge, correct? Well, I have heard that you do not experience acceleration, but I would think otherwise. Though you are moving relative to the object, and the Force that it applies to you should get anything with a mass of one to...

What is the most interesting astronomical object you have observed through a telescope?

Interesting new concept car-runs on compressed "air" link here : http://www.theaircar.com/ thoughts ?

Come across any interesting graffiti lately ? On the door of a math dept. classroom where Calculus was being taught : 1 + 1 --> 3, for large values of 1 Finger-written on the dusty rear windshield of a car parked near my apartment : I wish I had a woman this dirty

http://starbulletin.com/2004/06/28/news/story6.html How about a Doberman Chihuahua, or a Pekingese Mastiff? another interesting fact: http://en.wikipedia.org/wiki/Dog#Dog_breeds

If the Earth were hollowed enough so that a man could go to the center of it, assuming no magma, and be placed directly in the center of the Earth and assuming he was more or less symmetrical ( I know ... weird but go with me ) would he: A: Float in the center because gravity from all sides...