Homework Help

Hi everyone, I'm having a bit of trouble with this pde problem: i get the answer to be u(x,t)=0 but i am guessing thats not right. is the general solution to this problem: u(x,t) = f(x+ct) + g(x-ct) ?? thanks sarah

hmmm i have no idea where to even start with this problem, i cannot find any examples that are similar or anything like that anywhere! anyone got an idea as to a good first step to take? thanks sarah edit: i tryed something wild and came up with [math] A(u) = e^{u(x,y)} [/math] but i didnt use any knowlage of PDE's to work that out....hmmm.... :S

hi all, sorry again for the thousands of stupid questions! but heres another one... ok i said for part (a) that the PDE is a hyperbolic type and so has two sets of real characteristics. and that the characteristics are then for part (b) i used the coordinates: which leads to the equation: but then i am stuck... how can i get the 'general solution' from this, i think i am heading in the right direction, but i am not sure. any help would be greatly appreciated! thanks Sarah

lol my head is about to explode! i think this is similar to a previous question i asked but i can't quite get it none the less... now what i did was to following this : then using equations (31) & (32) from that i just plugged in the values and got: u(x,t) = 1 for x > ct and u(x,t) = 0 for 0 < x < ct how does this look to you intelligent mathematically inclined people? :S Sarah

Hi all, I am stuggling with this question ... so far i have only tried part (a), but since i can't see how to do that so far... ok so what to do... do we first look at an 'associated problem' ? ... something like lol, this stuff is all quite confusing -Sarah

here's a question I would like to ask, any could help would be appreciated. http://hk.pg.photos.yahoo.com/ph/loiyalunait/detail?.dir=/798fscd&.dnm=8900scd.jpg&.src=ph

I would like to ask two questions... the first one is about rheostat, which its resistance could be changed. R=V/I, when R increases, three cases are possible, V increases while I keeps constant; I decreases while V keeps constant; and V increases while I decreases at the same time, which of them is the case? http://hk.pg.photos.yahoo.com/ph/loiyalunait/detail?.dir=798fscd&.dnm=3d31scd.jpg&.src=ph the experimental set up shown in the above diagram is used to find out the relationship between resistance, voltage and current. when a current pass through the rheostat current and voltage decreases as the rheostat consumes enery, the current then flow through …

I'm kind of new here and not the greatest biologist (i think this applies in this forum) and was wondering if users could possibly help me out with something that has been baffling me. The other day my biology teacher for my Grade 12 Academic class showed us a little experiment involving homogenized milk, food colouring, and detergent. I'm aware that the milk is mostly comprised of water and contains some fats, that food colouring is water soluble, and that the detergent is an emulsfying agent (not quite sure what emulsion is), but that is were my knowledge ends. The experiment went like this: We took a petri dish and half filled it with the homogenized milk and let …

Question: An interior staircase has steps with a rise(height of step) of 18.5cm and a run(depth of step) of 21.9cm. The height of the staircase is 4.07m. It is desired to make the run of a new staircase 27.4cm. How much farther into the room will the new staircase go? (Answer to be in meters). I don't really get what they're asking for, I guess I just need help setting up the problem...

Choose one of the right answers:- A particle is thrown up vertically from a vehicle moving in a small path(with respect to cart).If we neglect dimensions of cart: 1) The particle will land back in the cart 2) The particle will land outside the circular path 3) The particle will follow a parabolic path 4) As soon as the particle is released it's acceleration becomes zero.

I need to answer the following question: Estimate the electrical power requirements of the complex by assuming that the complex has 10 family houses and two 12 storied apartment blocks. i was just wondering if anyone knew where this information could be readily available.. cause i dont really know what to search for ... well successfully anyway.. an help would be good. thank you.

hi, here r some questions i'm unable to answer. plz help me 1. Two particles A and B are projected from the same point with equal angle theta = 30 degrees from the horizontal. If A has the projection velocity VA = square root of 7 m/s and B has projection velocity VB = 2*square root of 7 m/s. find the separation 'd' between them when their velocity vectors become mutually perpendicular to each other. 2. 2 intersecting straight lines move translationally in opposite directions with velocities v1 and v2 perpendiculr to the corresponding lines. the angle between the lines is alpha. find the speed of the point of intersection of these lines. plzz post thes…

what will be the integration of 3x(3) + 4x(2) where (3)&(2) are the powers of x.????????

what does these line mean? "child is the father of man"

A sample of Na2S2O3 (aq) is titrated with acidified KMnO4 (aq) to a pink endpoint. One product of this redox reaction is SO4 2- (aq). A product of the reduction half-reaction is a. H + b. Mn 2+ c. SO4 2- d. S2O3 2- Please note that the numbers behind the letters are supposed to be subscript. I have no idea where to start. I know I should write some sort of half reaction, but with the info given, I don't know what the products would be!!!!

For question 13, which may be viewed as 3 in the tif, isn't the height giving out the same pressure, so my answer for it is that: iii has the greatest pressure then, ii = i . But the answer is i=ii=iii. Why? For the last question on the right bottom, I could predict the phenomenon but cannot explain it very clearly, May anyone explain it ? http://hk.geocities.com/quarkquarkquark2001/physics.gif I don't know why it can't be showed directly by IE but Firefox, it may be downloaded first. And, this is also my problem, can anyone explain this too?

I'm really struggling with what to do with this question..... A student designed a calorimetry experiment to determine the energy change for the following dissolving of ammonium nitrate and recorded the following results..... heat capacity of calorimeter and water........................228 J / degree celsiu initial temp of water..................................................21.6 degree celsius final temp of water..................................................16.4 degree celsius mass of ammonium nitrate...........................................0.250 grams The amount of energy involved in this change is ____ kJ. I've been fiddling with q = mc…

a) How many times must a die be thrown to be sure that the same number occurs twice? b) How many times must two die be thrown to be sure that the same total score occurs at least six times? c) How many times must n dice be thrown to be sure that the same total score occurs at least p times?

Sally constructed a dart board. The possible scores are 0,1,2,3. A score of 0 is obtained if the dart misses the board. Sally challenes John to a game consisting of each player throwing 6 darts at the board. The scores from the 6 throws are added. In how many ways can a total score of 15 or 16 be obtained? Note that the thw total score obtained from 1+0+0+3+3+2 is consisdered different to the score 0+0+1+3+3=2

Does electicity flow from positive to negative or from negative to positive? And Why is the direction of electrical current opposite to the direction of flow of electrons?

Hi, I am a graduate student it Turkey who is trying to finish her thesis. but I really need your help to finish it. There is a survey in the following URL. It is a simple survey takes at most five minutes of you. Also every 50. respondent is going to win an original Ferrari keyring. Please help, I need your ideas http://Turkey.speedsurvey.com

I'm currently taking this subject and I need help looking for cases to write in my journal. I have to pass it by the end of this month. Can someone please help me look for cases online? By cases I meant documented cases in counseling where the counselor has assessed the subject and put in details etc. as to his/her condition, the implications and carried out devices/means to help the subject cope with his/her condition. Thanks in advance.

Hi, I need help with the following questions, any help would be greatly appreciated Find the flaw in the following "contradiction": According to relativity, length (or distance) decreases and time increases as speed increases. Since speed is the ratio of distance to time, however, speed should decrease as distance and time increases In the Michelson-Morley experiment, no interference pattern was found. This meant that both light beams completed the same total distance in the same time. What would be a corresponding result in the boat-river analogy? what would be its signifigance?

The factors for 156 are 1, 2, 3, 4, 6, 12, 13, 26, 39, 52, 78, 156 grouped by last digit {1},{2, 12, 52},{3,13},{4},{6, 26, 156},{78},{39} Fenders are defined as factor enders. For example the fenders (factor enders) of 156 are 1, 2, 3, 4, 6, 8, 9 and that 156 is a 7-fender (that is, it has seven fenders). (Question 1) Show that a number which has 0 and 9 as fenders has at least four more fenders. (Question 2) The smallest 10-fender is less than 700. Find it and explain why it is the smallest.

Doing some revision and I've got a question I struggling with, it's not assessed. I'm having real issues with it: A particle of unit mass moves under a central force in the logarithmic spiral orbit, [math]r=ke^{\alpha \theta}[/math], where k and [math]\alpha[/math] are constants. Given the expression for accleration in plane polar coordinates [math]\bold a = (\ddot r - r \dot \theta^2)e_r + r(r \ddot \theta + 2 \dot r \dot \theta)e_\theta[/math] deterimine [math]\theta (t)[/math and r(t). Derive an expression for the force as a function of radias. My first idea was to differntiat [math]r=ke^{\alpha \theta}[/math] twice, reform it into [math]\thet…