What is Puzzle: Definition and 617 Discussions

A puzzle is a game, problem, or toy that tests a person's ingenuity or knowledge. In a puzzle, the solver is expected to put pieces together in a logical way, in order to arrive at the correct or fun solution of the puzzle. There are different genres of puzzles, such as crossword puzzles, word-search puzzles, number puzzles, relational puzzles, and logic puzzles.
Puzzles are often created to be a form of entertainment but they can also arise from serious mathematical or logical problems. In such cases, their solution may be a significant contribution to mathematical research.

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  1. ognik

    MHB Completing the Square in Fourier Transform: Right or Wrong?

    Hi - following an example in my book to calc. the Fourier Transform of the Gaussian. We need to complete the square to integrate the exponent, the power is $-a^2t^2+i\omega t$ ... - all good so far. Trouble is when I complete the square I get -a^2(t-\frac{i\omega}{2a^2})^2...
  2. themagician

    I Train vs Fly: Physics A Level Puzzle Explained

    I remember back at physics A level we were posed with the question of what happens when a train hits a fly. According to Newton laws the forces are equal, and so, by this theory, the fly should stop the train. We obviously knew that this didn't happen, but it took the whole class waaay too long...
  3. D

    Solve NPN Transistor Puzzle: -0.4V?

    I was just sent an email with the following text. "" Here is a puzzle I just encountered. Take any NPN transistor and ground the base. Now apply +12 volts to the emitter through a series resistor of 1k. Yes, it is a Zener diode of about 6 volts so about 6 ma of current flows.What is the...
  4. jk22

    B Proton Radius Puzzle: Muons vs Electrons

    Founding this : http://arxiv.org/abs/1502.05314 if I understood correctly the radius of the proton is smaller using muons instead of electrons. Could this be due to the fact that the gravitation force becomes repulsive at small distances so that the particles are kind of compressed by it ? I...
  5. M

    Puzzle of negative result of Michelson Morley experiment

    HI all How can Michelson itself predicted contraction of length and Einstein about constancy of light from negative result of MM experiment. forget about existence of ether, light speed always same in moving frame of reference and importantly in any direction so how can one except shift in...
  6. Kernul

    Weighing a Man on the Equator: Solving the Puzzle

    Homework Statement A man that has an ordinarily weight of 780 N stands on a libra on the equator. Homework Equations What is the weight measured by the libra? The Attempt at a Solution I thought it was simple, so I just did: P = m * g Since it gives me P I can simply do: m = P / g = 780 /...
  7. T

    Why Does Flow Rate Remain Constant When Reducing Orifice Size in a Water Tank?

    So we all know that due to the conservation of volume flow rate, reducing the diameter of a hose pipe would increase the velocity of the water flow.(A*V is conserved) But when the are of an orifice near the bottom of a water tank is reduced the velocity remains the same! Does anyone know why...
  8. Carnal

    What is the next shape in the series?

    I've been staring at this for hours but I do not get how the pattern works at all. The problem is from this website. It's not that I'm an idiot, I think there's something wrong with the pattern!
  9. D

    What is the TIS-100 programming puzzle game?

    I came across this new programming puzzle game on steam. http://www.zachtronics.com/tis-100/ The constraints of the machine make for some interesting programming puzzles. You get a grid of nodes. Each node can execute 10 or so really basic instructions (MOV, ADD, SUB, JMP, SAVE, SWAP). You...
  10. D

    Solving the Shorter Distance Puzzle with Spacetime

    I see an example from book stated that a muon that are created at high altitudes can travel to the ground because of time dilation about its lifetime. In the view of muon, it travels shorter distance compared with the view of the Earth. Suppose there are two muons. In view of muon A, muon B is...
  11. S

    MHB Logic Puzzle: Where is the koala?

    Anyone like riddles? I've got funny one. ​The Math Riddle Question: Where is the koala? There are five houses, each of a different color and inhabited by men from different territories, with one unique animal*, drink, and car. Some facts are given: 1. The Tasmanian lives in the red house. 2...
  12. H

    A puzzle on a Faraday cage "eating up" information

    Imagine an uncharged solid spherical conductor. Inside this spherical conductor, there is a cavity of a weird shape carved out of it. And somewhere inside this cavity, there is a charge +q. The charge +q induces an opposite charge -q on the wall of the cavity of the conductor, which distributes...
  13. Strilanc

    Is it Possible to Transmit Classical Information with Quantum Network Flow?

    This is a puzzle I came up with. I'm trying to judge whether the solution is obvious or not. Technically it's more closely related to quantum computation than quantum physics, but... let's try it anyways. We find ourselves with the following network: The goal is to find a way for the sender...
  14. R

    How Can You Extract Specific Signals from a 2D Image Using Fourier Transform?

    Suppose 3 1D Signals x(t), y1(t) and y2(t) are given as x(t)=sin(40*pi*t); y1(t)=.5*sin(40*pi*t) and y2(t)=x(t)+y1(t). Left side =Right side Here,values of x(t)and y1(t)i.e.(Right side) are given and we get y2(t)(Left side).The plots of x(t),y1(t) and y2(t) are plotted below...
  15. R

    Unlocking the Mystery of .999... and .333...: A Math Puzzle

    I just show how .999... = 1 Let x = .999... 10x = 9.999... 10x - x = 9.999... - .999... 9x = 9 x=1 So according to the above .3333... shows as 3. Let x = .3333... 10x = 3.333... 10x - x = 3.333... - .333... 9x = 3 x=3 But according to me, .333... should equal to .4 , isn't it? I must be...
  16. LAZYANGEL

    3 barrel question / logic puzzle

    First of all, this is NOT a homework question. So I give you three barrels, one has 50 apples, the second has 50 oranges, the third has 50 - a mixture of both apples and oranges. However, I have intentionally placed the wrong labels on all of them. Find the minimum number of fruits you need...
  17. M

    Egg Drop Ideas: Solve the Physics Puzzle

    Homework Statement I need help with egg drop ideas! For this project, I have to create something that will catch an egg (about 62.5 g) dropped from a height of 9.91 meters so that it will not break or crack. I also have to discuss forces, impulses, momentum, time and velocity changes of the...
  18. J

    MHB Generating Solutions for a Challenging Puzzle

    Hi, I'm doing some programming work with regards to this puzzle. Impossible Puzzle - Wikipedia, the free encyclopedia I have to generating the solutions to the the resulting solutions after the four following sentences are said. P says "I cannot find these numbers." S says "I was sure that...
  19. Alxb577

    Difficult Logic Gate Puzzle Using Only 2 Input NAND Gates

    Homework Statement [/B] Impliment the expression which is already in minimum sum of products form using only two-input NAND gates. No gate may be used as a NOT. All inputs are available both uncomplemented and complemented. (The number of gates required is shown in parentheses.) f = ab'd' +...
  20. PsychonautQQ

    Diophantine equations puzzle problem

    Homework Statement One hundred bushels of grain are to be distrubuted amongst 100 people. Each man gets 3 bushels, each woman gets 2 bushels, and each child gets 1/2 bushels. How many men, women and children are there? Homework Equations GCD, euclidean algorithm, Diophantine equation The...
  21. H

    MHB Help Solve This Financial Puzzle: Dropping Rebates Per Case

    Hi, I'm trying to prove something that I think is simple but am really struggling so would greatly appreciate any help! Over 2 weeks I receive rebates, the value of the rebate can vary both due to the rebate on each case and also the number of cases ordered. Between week 25 and week 26 my...
  22. V

    How many oscillations until a damped block comes to rest?

    Homework Statement A block of mass m is attached to a spring of spring constant k. It lies on a floor with coefficient of friction μ. The spring is stretched by a length a and released. Find how many oscillations it takes for the block to come to rest. Homework Equations d2x/dt2 + k/m x = +_...
  23. A

    Polarization of clear plastic - a puzzle

    I finished my online E&M class today, and the prof told us to experiment with polarizers. While doing that, I found this: I put a piece of plastic between two polarizers, and found that at a certain angle between the two polarizers, a portion - though not all - of the plastic darkened. So I...
  24. C

    Solve Physics Puzzle Problem - 200 Puzzling Physics Problems

    So I've been trying to do some physics puzzles and I've come across this in a book called "200 puzzling physics problems." The solution in the back makes no sense to me and I can't seem to figure it out by myself. Can anyone help me?
  25. A

    Quantum harmonic oscillator tunneling puzzle

    My problem is described in the animation that I posted on Youtube: For the sake of convenience I am copying here the text that follows the animation: I have made this animation in order to present my little puzzle with the quantum harmonic oscillator. Think about a classical oscillator, a...
  26. J

    The elevator, the scale, and the wrong answer: Solving the Puzzle

    You walk into an elevator, step on a scale, and push the "up" button. You recall that your normal weight is 625N. If the elevator has an acceleration of magnitude 2.50 m/s^2, what does the scale read? I know how to solve this problem, but I don't know why I'm getting the wrong answer. I first...
  27. stephenranger

    Solving the Car Parking Lights Puzzle: Current, Resistance & Time Calculations

    Homework Statement A total charge of 50 Ah is stored in a 12 V battery of a car. Each of the bulbs of the four parking lights is labelled 3,6 W / 12 V. Homework Equations a) Find the current from the battery when only the parking lights are switched on. b) What is the resistance of one bulb...
  28. quantumdude

    A Puzzle: Find an Ellipse Tangent to a Circle

    I was asked to look at a problem (not homework) in which a tangent ellipse is to be found for a circle. This puzzle is turning out to be more than I bargained for. See the attached image because hey, a picture's worth a thousand words. The givens in this problem are to be the radius ##R_i## of...
  29. M

    MHB Solving the City Soccer Tournament Puzzle: Group A Results

    My daughter needs my help, and I am stumped. Here is the problem: In the first round of the city soccer tournament, the teams in group A finished as follows: Team------>Goals For------>Goals Against----->Points Naranja---> 4--------------->2-------------------->7 Bleu------>...
  30. N

    Solve 3x3 Numerical Puzzle: Can it Be Done?

    1. In a 3 x 3 square, place the numbers 2,2,2,3,3,3,4,4,4 in it so that when any line of three numbers is added up in any direction (including diagonally) the total is always 9. 2. I have tried for hours, can anyone tell me if this problem is actually possible? The best I get is when I do 234...
  31. Ludwig

    Uniform Circular Motion puzzle

    The position function for a particle moving on a circle (with constant speed) is: ## \vec{r}(t)=\left \langle r\,sin(t), \, r\,cos(t) \right \rangle ## Taking the first and second derivatives, ## \vec{v}(t)=\left \langle -r\,cos(t), \, r\,sin(t) \right \rangle ## ## \vec{a}(t)=\left \langle...
  32. M

    Trivial/pointless math puzzle I'm too stupid to solve

    Pretend you own a printing press and you want to be able to represent any arbitrarily large natural number. You also want to store the fewest possible number of characters in your collection, just to save space. What base, if any, would yield the largest ratio of numbers you can represent to...
  33. G

    Solving the Homework Puzzle: Finding Your Error with Surface Integrals

    Homework Statement The problem is given in the attached file. Homework Equations Divergence theorem, flux / surface integral The Attempt at a Solution [/B] As you can see I got the question correct using Divergence theorem. But I wanted to make sure that I could arrive at the same answer...
  34. I

    C/C++ Solving the Loop Puzzle: Shifting Old Scores to New Scores

    Write a loop that sets newScores to oldScores shifted once left, with element 0 copied to the end. Ex: If oldScores = {10, 20, 30, 40}, then newScores = {20, 30, 40, 10}. Sample program: #include <iostream> #include <vector> using namespace std; int main() { const int SCORES_SIZE = 4...
  35. Dai

    MHB Solve the Math Puzzle: 66+935+1389

    If 28+453+9012=81.534 91+712+1024=49.091 Then 66+935+1389=?
  36. L

    What's the Solution to this Saturday Puzzle?

    Hey all, I'm new here and thought I'd introduce myself by providing you with a nice puzzle to solve. Answers to be sent with reasons! LePuzzled1
  37. R

    A clock tower puzzle in a gravitational field

    In General Relativity spacetime is described by a metric. The most common one is the Schwarzschild metric, valid at radii greater than the surface radius of a mass. If we assume constant angular position so that dθ=dø=0, then this metric relates local (proper) coordinate time and distance dτ...
  38. J

    How Does Relativity Affect Observations of Approaching Spaceships?

    Two spaceships approach an observer from an equal distance and from an opposite direction with an equal speed in the observer's intertial reference frame O. The speed of a spaceship in the intertial reference frame of the other spaceship S is 0.8c , what is the speed of one of the spaceships in...
  39. N

    Division by 0: A Puzzle That Has Baffled Us for Years

    Hello This is question is bugging me for years. Why is division by 0 undefined and not multiplication by 0 undefined? If any number multiplied by 0 is 0 then the logical answer for any number divided by 0 would be ∞ (for me at least). If you "define" N/0=∞ and N*0=undefined then there are...
  40. W

    MHB What is x when c is at maximum?

    a = x^2 + 2cx + 1 b = 2x + 3c + 3 a / b = 5 plus a remainder of 11. c=? Want to include above in a "puzzle" site. Want see if it makes sense.. Can you solve it? Than you.
  41. B

    MHB Math puzzle: getting 2L from 3L and 4L containers

    If you have one 4 liter container and one 3 liter container how do you measure 2 liter of milk by using them? Please explain in detail
  42. Adjoint

    (Puzzle) How can this be true?

    Am I getting dumb for some reason or is this a good puzzle? PF friends! What am I missing here? Really, from where did that empty block come...
  43. Algr

    Solve the Puzzling Mystery of the Speeding Plane

    I was debating putting this up in General Physics, but since I already know the answer, I thought I'd put it here. I also put this in some other places to see how different forums would react - my own little experiment. =========== A true story: I once took a car GPS with me on an airplane...
  44. A

    MHB Solving the Lawn Mowing Puzzle: Explained!

    So person A takes 1 less hour than person B to mow a lawn, Person C takes twice as long as Person B to mow a lawn. All together they mow a lawn in one hour. How long does it take each of them to mow a lawn working alone? Can someone explain this to me please, thanks.
  45. V

    Solving the Diode Puzzle: Finding V with Diodes

    Homework Statement Hi so I have a problem that I don't exactly know how to approach, here's the diagram: http://images.fr1ckfr4ck.fastmail.fm/probA.jpg The diodes are supposed to have saturation current I_s = 10^(-15) A Homework Equations What is V? The Attempt at a Solution First I tried...
  46. D

    Solve a Laplace transform puzzle

    Hi~ I recently solve a Laplace transform problem as following L[int{t,0}cosh(t'-1)U(t'-1)dt']=? U(t'-1) is the unit step function(=1 for t'>1, =zero otherwise) According the standard Laplace formula : (1)L[cosh(t-1)U(t-1)]=exp(-s)*s/(s^2-1); (2)L(int{t,0}f(t')dt')=F(s)/s...
  47. D

    MHB Can a Math Genius Help Solve This Puzzle?

    Hello everyone. I am trying to complete a programming challenge, of which I have taken a screenshot of and posted on flikr. I was wondering if there was some math genius on here who could help me solve the puzzle. Forget about the programming part, I can do that. All I need is some advice on...
  48. R

    Solving the Inclined Plane Puzzle

    This is driving me nuts. What am I missing? Suppose you have an inclined plane with a mass m resting on it. The free body diagram for the mass m has F_grav downward and F_normal perpendicular to the surface of the inclined plane. Thus, by Newton's Second Law, you have: ∑F=F_grav+F_norm=ma with...
  49. S

    Engineering Finding Vo Using Node Voltage Method: A Calculator Puzzle

    Homework Statement Find the voltage Vo using node voltage method specifically.Homework Equations The Attempt at a Solution I am able to get the correct answer when finding the equivalent impedance, then determining the current, and then finding the voltage at the first node V1 by subtrating...
  50. A

    Puzzle with moment generating function for gamma function

    I am given that The kth moment of an exponential random variable with mean mu is E[Y^k] = k!*mu^k for nonnegative integer k. I found m^2 (0) = (-a)(-a-1)(-beta)^2. The answer I found is however mu^2+a*beta^2 which is different from the k! From the given formula. Could someone help me figure it...
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