Mystery Definition and 872 Threads

why r^2?? hi I have a big problem in physics that nobody could answer it until now.I hope that you can help me. my question is about this formula:F=Gm1m2/r^2 why r^2?? :confused: I searched about it very much but the only thing that i could find was this:the answer is not:because of the...

I have searched for this answer all day long. Why is Vave multiplied by 2 to obtain Vf?

Okay, here's the deal: Basketball player Darrell Griffith is on record as attaining a standing vertical jump of 1.2 m (4 ft). (This means that he moved upward by 1.2 m after his feet left the floor.) Griffith weighed 890 N (200 lb). (B) If the time of the part of the jump before his feet...

why is sea water salty ?

Hi, Anyone out there have Lawden's book, "An Introduction to Tensor Calculus, Relativity and Cosmology"? Expression 39.13 (on p 109) and the sentence that precedes it have me stumped. My understanding of what he's saying is that a symmetric quadratic form can always be diagonalized so that...

Why did nature never invent the wheel?

this item is about the size of your hand, 3d, and it is considered *normal* if a stranger walks up to you and gives you the item. You will know what to do with it, and you will give it back when you are done, despite it being worth a considerable amount (it varies). by asking me only yes/no...

What volume of 50% NaOH (by weight) solution is necessary to prepare 1 litre of 0.1M NaOH? Assume that the density of the NaOH solution is 1.53g/ml.

This is a 'How did I do this?' teaser. A couple of notes first: - The picture I include is simulated (Googled for a generic shot). Sorry, best I could do without the original. Ignore the fact that a] it's not me, and b] that the pic is indoors. - Even though this is a simulation, I actually...

VSEPR Theory... I am completely at ease with being able to use VSEPR theory to answer questions, etc, but I just can't get my head round why it actually happens? All I am told is "electron clouds repel each other to be as far apart as possible", but this seems to completely disagree with the...

Why do females live longer than males?

A Cow's Dance A cow named Dolly was enjoying the pasture & turned to face the setting sun. Then, she decided to do a little dance. The following are the steps: she turned 180degrees to her right, 90degrees to her left, then another 45degrees to her right. She repeated the steps 250 times. At...

http://www.tessproject.com/products/seminars&training/seminar%20series/Assets_Materials/The_Mystery_of_Capital.pdf

Hello everybody! What's the number of possible configuration of a Rubik cube 2x2 (allowed movements are like in a 3x3 cube but here there are not central pieces that don't move). THanks for your help

I don't get where these two identities come from: (logn)^{logn} = n^{log(logn)} and (logn)^{log(logn)} = e^{(log(logn))^2}

Are the whole processes of DNA, RNA, ribosomes, amino acids and proteins all just "chemical reactions" or is there something more to it? I know the way it works from DNA to protein but why? I understand this question might have a very complex anwser but a brief explanation would be...

Rate of decay... "The rate of decay is durectly proprtional to the number of atoms present, following an exponential law, the rate of decay decreasing with time" - but why is this the case? Thanks in advance. :smile:

hi , i recently found while playing around with my new calculator that any number repeated six times is divisible by 7 ... for eg, 4 repeated 6 times gives 444444/7 =63492 an say 761 repeated 6 times 761761761761761761/ 7 =108823108823108823 the last one was done using a computer...

what is the reason why the number of H- ions in a gas must always be less than the number of HII ions?

Why does dry asphalt appear to be wet on a hot, sunny day?

I have a question regarding fluids A small sculpture made of gold (density of gold = 19280 kg/m^3) is believed to have a secret central cavity. The weight of the sculpture in air is 25.76 N. When submerged in water, the weight is 23.86 N. What is the volume of the secret cavity. (Density of...

What is the actual name for the integral symbol? I know it was first used by Leibniz, but did he actually call it anything...? It's really hard trying to convince my friends the integral symbol is the sexiest thing ever invented, when I don't even know her true name. :blushing:

I have a sample of 25 % acetanilide with 75 % caffeine. I record a melting point range of 198 - 240 degrees celsius acetanilide's melting point is 114.3 caffeine's melting point is 238 What would cause this huge experimental range? My thinking is that the acetanilide is...

I'm trying to write a program that would process data from a particle physics experiment and I need to know what the charge of a muon/anti-muon is. It doesn't seem to be easy to find on the web. Does anyone here have a value for it?

Is it know why the Earth's core, and indeed the cores of other planets, are "hot" while some are cold? Is it possible that fusion or fission processes are taking place there ?

x=--x wtf =/ (this isn't a homework problem but it was brought up today and I'm curious) :confused:

[FONT=Arial Black]undefinedundefinedundefined I have a mystery alkali carbonate. I need to react it with sulfuric acid. When this occurs I know the products are carbon dioxide, water, ions of the mystery metal in solution and ions of sulfate in the solution. My question is how do I find the...

Why isn't there such a thing as base rain? Or do we just never hear about it?

hey everybody, I am new to the forum, and glad to be here. looks like a great place for help when all has failed! :cry: if you race 2 cans of broth down a ramp, one frozen and one still liquid, which one wins? well, i did this mathematically, using the equation for a solid ring...

Ok, here's the question: A skier starts at the top of a very large frictionless spherical snowball, with a very small initial velocity, and skis straight down the side. At what point does she lose contact with the snowball and fly off at a tangent? That is, at the instant when she loses...

How does a plasma ball work? http://www.iwantoneofthose.com/PLABAL_GADG.htm

Under special conditions, sulfur reacts with anhydrous liquid ammonia to form a binary compound of sulfur and nitrogen. The compound is found to consist of 69.6% S and 30.4% N. Measurements of its molecular mass yield a value of 184.3 g/mol. The compound occasionally detonates on being struck or...

what the !? ok idk if I am right and the book is wrong but help me out the question is... An electron moving at a speed 0.60c collides head on witha positron also moving at 0.60c. Determine the energy and momentum of each photon produced in the process. well this is what I did.. E =...

Hi All Why DNA molecules alone replicates itself were does self property of ( memory ) to replicate comes from ? why not other macro moloecules like proteins ( expect pirons :biggrin: ) don't replicate like DNA :confused:

Fermi Numbers!?? I'm trying to solve this problem and explain all my steps in my reasoning. **HOW MANY HAIRS ARE ON YOUR HEAD?** If anyone can help me figure this out, reply thanking u in advance faiza

I have a smal brain but am trying to help an elderly gentleman (who doesn't speak too good English) with his theories. He talks about a "twon" or tuon in relation to the rapid deceleration of photons, producing eletron-positron pairs. I can't find any particle or process similar to this...

You are in a room with 3 light switches. These switches are connected to 3 separate light bulbs in an ajoining room. Access to the ajoining room is via a door that remains closed, there are no windows, other people etc etc. You are allowed to enter the ajoining room once and then return. At...

Mystery : Myth & History - yet another trivia quiz This is advance warning that I'll put up the actual quiz here in about a day. Also, I'd like to dedicate this quiz to Ivan Seeking and Evo, the irreplaceable Guardians of the PF Lounge. < hope I chose the theme wisely >

here is a part of the protocol we did: a)spin down the chloroplast solution and decant the supernatant. add 4ml water to the pellet. b) add 10ul proteinase K ( concentration= 20mg/ml) to get a final concentration of 50ug/ml. -> how do they get 10ul? which formula do they use? i don't...

Can someone explain how it is possible that the speed of light is constantly 670 million mph irrelevant of relative speed? how is it that you can be going 669 million mph yet light still accelerates toward you at the same rate??

My anti-spam Email account is suppose to be basically spam free. However, today I received an Email which may have contained a virus and a message I could not read. My provider blocked both from my account. The title however was "I cannot forget you!" The Email's domain contained the...

Hi all. Imagine one negative charged dielectric rod into a copper solenoid, and rounded coaxially by another positive charged dielectric. Then we have an E field radially directed passing through the coil. Now put one magnet on top of the coil and another magnet at the bottom of the coil...

I was just messing around and ran across this site that hate math facts on it and I chose a random one about a football field. Here's a http://www.math.hmc.edu/funfacts/ffiles/10010.2.shtml# the fact. Now, I understand what they're trying to get it, but what I don't get is how they came up...

If there is a single atom of water or some substance, can it have the properties of a solid gas or liquid? Or is it a separate state?

Ok i don't know if you ppl know these http://storeforknowledge.com/stores/163/images/lightning%20ball%20large.jpg How do these work?

Another one of the physics teacher working at the college I attended (see my previous post) wrote a book on basic http://universite.deboeck.com/Resources/Titles/28011100266200/Images/28011100266200L.gif . In this book it says that the expansion of the Universe is due to the expansion of space...

ok so I've got this equation M1 = T1^2 M2 __T2^2 the _s are only for spacing purposes can anyone tell me what it is for? I think the M is mass and the T is tension but I really have no idea

Last decade ice core digging in the West Antlantic Ice Sheet (WAIS) gave a big surprise. Diatoms in the mud under the ice sheet revealed that there has been a sea bottom with a maximum age of some 500,000 years but possibly younger. http://www.sciencemag.org/cgi/content/full/281/5373/82...

We have a box in which there are 2 white and 3 blue hats. The light is turned out and 3 boys take at random one hat each and places it on his head. The light is turned on again. Each boy can see the colour of the hat of each of his colleagues but not his own. The first boy is asked the...

Hi! I understand that according to E=mc^2 any normal object can't reach the speed of light because the energy of its motion increases its mass and thus you'd need an infinite amount of energy to reach c. However, it is said that objects with no mass (i.e. photons) travel at the speed of...