Puzzle Definition and 618 Threads

On a recent Car Talk Show there recently was a puzzle from the "Hat in the River" series. The hosts of the show emphasized that the puzzle should be solved by thinking and not by using algebra which may confuse things. So instead of thinking I tried to use algebra to try to solve the puzzle...

Let H be a house with only one entrence. Assume that between any two rooms in the house there can only be at most one door. The owner's of this house, keen on selling to an American buyer, decide to place a TV set in every room with an odd number of doors. Prove that the the American will be...

Dear friends of MHB Yesterday my attention has been attracted by the following article… http://www.huffingtonpost.com/2012/05/27/shourryya-ray-16-year-old_n_1549172.html It seems that a 16 old student named Shouryya Ray and ‘dubbed Genius’ has ‘cracked’ a puzzle that Isaac Newton proposed...

Hi, I am not able to comprehend the solution of a problem from a puzzle book. Your friend shows you an urn and tells you that there is one marble in the urn. The marble is either black or white. (Assume that the marbles are identical in shape and any two marbles with the same color are...

Here's the puzzle: http://9gag.com/gag/4137344 Now, I did this fairly quickly with the right tools(another use for excel found). However along the way I had to make 2 assumptions/random guesses: The yellow vs dunhill in houses 1 or 3 The dane vs tea in houses 2 or 5 Question being, can this...

I have this in my home work and i am not 100% on if i have it right or not A converging lens with a focal length of 25 cm is used to make a slide projector. If the image is to be projected onto a screen 10m away, how far should the lens be located from the transparency? I did it like...

Hi, My question is related to a math puzzle. The puzzle asks to swap any two digits from the numerator with any two digits in the denominator of the fraction 1630 / 4542 to get the ratio 1 / 3. Two possible answers are 1534 / 4602 and 1354/ 4062. What I am struggling with is the number...

Homework Statement Weight suspended by 3 cords. 1 from the weight goes up vertically to the knot. The next goes left 30° below horizontal and the last goes to the right 45° above horizontal. Homework Equations f=ma The Attempt at a Solution I don't think I've ever worked a problem...

Homework Statement (see attached files) basically, I have to solve a puzzle game simulated by matlab. In a school of n students with n lockers, each student opens and closes a locker they walk by. all the lockers start the game closed. the first student changes every locker's status...

Imagine Batman has a new hyper speed Batship that is the shape of his circular bat emblem. The ground has convenient square grid on it and when parked on the ground the ship is exactly the same length as a square on the grid and its shadow touches the four sides of a square. Mounted underneath...

I might misunderstand the higgs mechanism. And I have a puzzle. Consider an electron in an accelerater. It is massive at low energy and its speed is something lower than the speed of light. However when it is accelerated to the electroweak scale, su(2) becomes unbroken and the electron turns...

Let n=79 phi is Euler totient Can you find a number k such as : phi(k)=0 mod 79 phi(k+1)=0 mod 79 phi(k+2)=0 mod 79 phi(k+3)=0 mod 79 ... phi(k+78)=0 mod 79 phi(k+79)=0 mod 79 Good luck!

I made up it, I didn't find anything about it, so, maybe, I'm the inventor. The question is: How do different set theories handle the following definition? U := {x : (x belongs_to A) and ( Not(A is_included_in Powerset( EmptySet)) )} If possible in the set theory, require (A is_set). But it...

I have an integral in my math text that I cannot seem to tackle, help would be appreciated. thanks! I am not really sure where to start. \int^{1}_{0}\frac{dx}{\sqrt{log(\frac{1}{x})}}

Saw this puzzle during an interview for programmers. Thought it was kind of clever. Can the domino tile the chessboard with no overlaps, no overhangs and no half tiles? If so, how can you prove it? If not, how can you prove it? No, this is not a trick question (or trick answer).

Homework Statement Five players each have a different (given) number of mice in their bags. Each player also has his own hidden mouse treat behind his back, which mice may or may not be able to sense. All players open their bags at the same time, allowing mice to move freely between bags if...

hi there, new member and this is a bit off a puzzle to me (this isn't homework its something I am trying to use for a little simulation game haha) ok so the puzzle involves a ball being projected, i am wanting to find the minumum hight it can travell with the longest distance (does that make...

I came across this puzzle in the book The Big Book of Riddles Puzzles and Enigmas and I am also certain I have seen it elsewhere throughout the internet. The puzzle as written goes like this "A troubadour holding three objects (a ball, a hat, and a bowling pin) arrives at a bridge. The...

I was hoping some of the brilliant minds here might share their thoughts on the following puzzle: Definition. A valid clock position is exchangeable iff swapping the positions of the minute hand and the hour hand yields another valid clock position. Example. Midnight is an exchangeable...

This is a repost of an old thread, maybe some new members can give it a shot. This puzzle was included at the start of a casual IBM Fortran programming class for high school students back in 1969. (Yes, I'm that old). I don't know the origin of this puzzle. An extremely simple and old...

So I have got answers to this logical puzzle. However, I feel ill and slow. I have checked this over and over and I am 80% it is totally correct. To make sure I would like a second opinion. Do you get the same answers? The puzzle is in quotes: "Vera, Winifred, Xanthippe, Yvette and Zelda...

Homework Statement What is the ratio between times for the aliens to hit the floor. you have two spheres of equal density throughout. One has a radius R and the other 1/2R. An alien falls down one and takes time T, the other it falls down in time t. In the second on, time t, half of the mass...

This actually happened to me in a hotel in Bali. It was night time and a light from the street was reflecting off of the mirror onto the wall. In front of the mirror was a statue of a goddess. Projected onto the wall were two separate shadows of the goddess, rotated with respect to one...

Homework Statement A 20 Kg Wooden crate rests on the wooden floor of a warehouse. What is the minimum horizontal force which must be exerted on the crate to get it to start sliding across the floor? Once it starts to move, how much force is needed to keep the crate moving at constant velocity...

My 2 year old play with the following toy at our home. https://www.amazon.com/dp/B000GKD006/?tag=pfamazon01-20 It is basically, when you put the correct animal block in the correct place, it makes the sound of that animal. I can see some sensor in the wood piece and in the board; it can...

Homework Statement My class is required to write the Java source code for a 15 Puzzle program as an end of the year assignment. http://en.wikipedia.org/wiki/15_puzzle" is a link to what the 15 Puzzle is, for those who aren't familiar with its name. The assignment is split into two parts...

“As per Inspector Lestrade, the accused house is on the bank of a river which is quarter mile wide and has current of 2 mph“. said Dr. Watson “Don’t forget Watson, Just opposite his house, on the other bank, is the victims house. The accused has only to swim across!” Sherlock Holmes...

Recently, my friend tested me on a puzzle. The puzzle goes like this, if there is 8 balls (1 of them which weighs either lesser or heavier), how are you going to find out which is the different ball using a two sided weight scale with 3 tries? This is a pretty easy puzzle which everyone would...

One key aspect of Special Relativity is the fact that nothing can travel faster than the speed of light. This concept derives from Maxwell's Equations, which calculate the speed of light (electrodynamics). Since Maxwell's Equations describe the formation of magnetic fields (as a result of...

Homework Statement in the given diagram all the stings and pulley are mass-less ad there is no friction calculate the magnitude of acceleration of the two blocks? Homework Equations The Attempt at a Solution the acceleration of the blocks is obtained by me to be g/20 but...

There has been so much interest lately in objects going faster than the speed of light, I though I would propose a little thought experiment. An observer is standing stationary relative to Object A, which is 1x10E10 meters away. Since there is no relativistic limit on acceleration, suppose...

Hi. I'm I law student in my fourth year. We have a subject called Practice Court wherein we are trained and taught how to act as lawyers in court. Now here's the problem, the case that was assigned to us was about a vehicular accident. In our defense, I suggested a very ridiculous and difficult...

I have a puzzle when I study the hybrid inflation model. Suppose we have two scalar fields, \phi_1 and \phi_2 first, let's consider the situation where they are in their independent potentials V(\phi_i)=m_i^2\phi_i^2, i = 1,2 with initial value \phi_i^{ini} We can solve the scalar...

Homework Statement http://answers.yahoo.com/question/index?qid=20090812013110AAcrnFs Homework Equations Equilibrium - Fx = Fcos(theta), Fy = Fsin(theta) The Attempt at a Solution I've got the answer however it's different to the one posted the link above - isolated the top pipe...

Here is the Problem. http://img577.imageshack.us/img577/3769/screenshot20110803at231.png Uploaded with ImageShack.us I know the first part where the signal goes from A to B and i know what the signal will look like at B, as i used the inverting op amp formula. Vo=Vin x -Rf/R1 I understand...

A natural integer N can be written as x mod p, for instance: N... 1 2 3 4 5 6 7 8 9 10 11 12 p=2 1 2 1 2 1 2 1 2 1 2 1 2 p=3 1 2 3 1 2 3 1 2 3 1 2 3 p=5 1 2 3 4 5 1 2 3 4 5 1 2 p=7 1 2 3 4 5 6 7 1 2 3 4 5 Etc. The puzzle is quite difficult to state in this format but I'll have a go: You...

Imagine a cube wrapped in Latin squares and try to solve the following puzzles. Please be aware the symbols at the borders are shared between neighboring cube's sides. Let me know if you like it or not. This is rather straightforward: This is a bit harder

What is the difference between Electric potential & Electric Potential Energy?lWhat is the physical significance of Electric Potential?

I have a battery that I was hoping to use to power my dvd player however it says that the battery is 12volts at 3amps and my dvd player says it is 12 volts at one amp can I successfully use this battery which is 12 volts at 3 amps to power a dvd player that says 12 volts at 1 amp any help is...

Physics puzzle: A 1" radius 7 billion K temp. ball is activated inside Jupiter... Physics puzzle: A 1" radius, 7 billion K temp. fireball is activated inside Jupiter...from an artificially induced fission reaction of .04kt. It is activated deep enough into Jupiter to be under 40,000,000...

Given any two random tile arrangements in a sliding tile puzzle, is it always possible to find a way to go from one to the other? It's trivial to prove that this isn't true for 2x2 puzzles, but I don't know how to approach the problem for bigger sizes, short of brute forcing it with a computer...

I noticed many PF threads mention ground state of Hydrogen atom. At the same time it is two body problem considered to be solved by separation of variables. It is true, of course, that we can find basis wave functions (solutions of Shroedinger equation). But why does anybody think, that...

Quick! Without factoring or using any multinomial theorems, give me the coefficient of x17 in the polynomial product: (x3+23x)(x6+35x4+1685)(x19+1246x9) Can you do it?

I just bought lunch at Quizno's. On top of a cabinet, between the cash register and the fountaion drink machine, in essentially the most prominent place in the establishment is this little framed 3" square metal plaque. It's like a little boiler plate off a machine - the lettering is stamped...

lol...the task is sisyphean for sure. http://www.highiqsociety.org/Sisyphean%20Airlines%20Puzzle%20Challenge.pdf

A function f that is analytic in the whole plane does not take any value more than 3 times. What can it be?

Im working with building a reluctance motor and I've posed a problem to myself that i cannot answer without questioning some long accepted facts about the inductance of a solenoid. The simple solenoid and toroidal solenoid are two shapes that seem to have simple equations for calculating the...

Describe a simple way to force a particle to move along two different circular trajectories at the same time. (Two circles that are not concentric) Hint: The trajectories do not have to be measured from the same frame of reference. It need not be an elementary particle (could be even a small ball)

After typing all of that out, I think I got it, thanks! Homework Statement I am working on a project to build a biodiesel reactor. The heating system of said reactor is provided by a loop of pipe containing a pump (1 HP, 36 litres per minute (9.5 gal), 50m max head (164 ft)), a hot water...

Sometimes we need to calculate the evolution of the scalar field \phi with the equation of motion \frac{\partial^2 \phi}{\partial t^2}+3H\frac{\partial \phi}{\partial t}+m_\phi^2 \phi = 0. And we can get the field \phi=Ae^{im_\phi t} where A is the amplitude of the scalar field (damped by...