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  1. R

    Fluid Dynamics: Bernoulli's?

    ya sorry ..I phrased it poorly. I This question is part A. I can calculate a velocity 10.2 m/s which does appear on the list yes. However when I move to part B it wans to know what the velocity V3 of the lower section is. I use conservation of mass to determine this and i get an answer of...
  2. R

    Fluid Dynamics: Bernoulli's?

    attached is the problem. I use bernoulli's equation along a "streamline" from the inlet at point 1 to outlet at point 2. I do this to obtain the velocity V2. After working through it (simple algebra) I end up with 10.20 m/s ...seems right to me... however upon doing a conservation of mass...
  3. R

    Laplace transform

    ahh thanks.. we actually learned convolution theorem last week...but I was unsure of where to apply it.. I've been trying the convolution method for the last hour and apparently I'm not applying it correctly. and in my table there are general laplace transforms yes but not any for something...
  4. R

    Laplace transform

    Hello I'm struggling to understand some basics here with the laplace transform.. I'm given the laplace transform of 2/(s + 4)^4 and I need to take the inverse of this to get back to y(t) Looking at my tables the only transform similar to this is 1/(s + a)^2 I understand I can pull...
  5. R

    Electrical Circuit - Power dissipation

    actually that is exactly what your talking about... i just drew it out with the source and a resistor in series and did KVL and yes i totally understand now... but basically this is not giving true power dissipated by the circuit is it not... its now including power dissipated by the power...
  6. R

    Electrical Circuit - Power dissipation

    im not 100% sure what you mean by that but I am assuming you mean... an ideal DC power source has 0 losses and a non-ideal power source does have losses?
  7. R

    Electrical Circuit - Power dissipation

    During a Lab we had a simple purely resistive circuit hooked up to a 10 VDC power supply with an adjustable voltage output. In order to determine the power dissipated by the circuit we were asked to determine the source voltage while the circuit was DISCONNECTED... we were not told why... In the...
  8. R

    Shifting Coordinates question

    that makes a lot more sense maybe the graphic that goes along with the question was throwing me off... it shows a stadnard x,y and then the p-q axes rotated and shifted. we are taught to do this with a rotation matrix etc.. the way you explained it makes perfect sense though if i think...
  9. R

    Shifting Coordinates question

    I have to revisit this thread. I'm still having a difficult time conceptually/graphically understanding this. So we're dealing with a graph of velocity. Which would be distance vs time graph correct? or do you interpret this as a velocity versus time graph? I am having a really hard time...
  10. R

    Shifting Coordinates question

    Interesting, thank you very much. I will think about that one for awhile !
  11. R

    Shifting Coordinates question

    the more i think about it the more it bothers me... Moving the origin of a coordinate system without moving the point is exactly the same as moving the point,while keeping the origin fixed. which is exactly the same as creating a new vector with a different magnitude and direction?
  12. R

    Shifting Coordinates question

    Well that is indeed how I arrived at the answer the first time, is by making a transformation matrix and not shifting the co-ordinates origin. however this is what's really confusing me, I thought for sure (especially with a velocity vector) it would make a big difference where the coordinate...
  13. R

    Shifting Coordinates question

    I'm stuck on this question.. I have achieved the answer by fluke but would love help understanding the process its driving me nuts... The velocity of a ball in an x-y coordinate system is (10, -5) where distance is measured in metres. A second coordinate system, p-q, uses units of feet (1 ft...
  14. R

    Gauss's Law and electric flux

    Oh excellent, so judging by what you wrote to continue past where I left off it involves a double integral? if this is the case I have not learned the double integral yet this semester which makes more sense why I as so stuck ..
  15. R

    Gauss's Law and electric flux

    Can someone please help me work through this problem I've spent over an hour on this trying to figure out what to do.. here's the question A nonuniform electric field is given by the expression E = ay^i + bz^j + cx^k, where a, b, and c are constants. Determine the electric flux through a...
  16. R

    Indefinite Integral of a contant function

    This question is bugging me if an indefinite integral is of the form F(x) + C stating that F(x) is an antiderivative of f(x) and since the derivative of a constant is 0 the collection of all of the anti derivatives are of the F(x) + C accounting for the fact any constant can be tagged to the...
  17. R

    Notation clarification

    I understand that part, its the actual meaning of the symbol dQ... or dx for that matter that I am looking for what I am finding so far is that dQ could mean an infinitly small portion of a larger charge Q
  18. R

    Notation clarification

    I'm taking a calculus based physics class this year and I've had a few issues getting reliable information on the following notation the following equation I = \frac{dQ}{dt} the previous equatin represents the instantaneous current in a conductor. what exactly is the term dQ or dt...
  19. R

    Indefinite integrals

    thank you very much ! very helpful to me! not even my textbooks could explain that part as clearly as you.
  20. R

    Indefinite integrals

    This is really a full on homework question but it WILL help me to solve my homework... by helping me fully understand the integral. So I am trying to understand exactly what the indefinte integral means? heres my train of thought... if our function F(x) = x2 then its derivative is F'(x)...
  21. R

    Taylor Polynomials- Lagrange remainder

    so for the remainder term... if Xo = 1 ... the point its centered around I am assuming... and x = 2 for estimating e2 I should pick a value Z in [1,2] such that it creates the maximum amount of error i may get ?
  22. R

    Taylor Polynomials- Lagrange remainder

    So I'm studying for a final, and it just so happens my professor threw taylor polynomials at us in the last week.. I understand the concept of a taylor polynomial but i need some help fully understand the LaGrange remainder theorem if we have a function that has n derivatives on the interval...
  23. R

    Dot product vector question

    nm its all good i got it figured out thanks !
  24. R

    Dot product vector question

    excellent thank you, I thought that was the method but I'm still running into trouble expanding cos(x + 25) and dividing to clear... when i expand i get cosx / (cos(x))(cos(25)) - (sin(x))(sin(25)) = 6/7 i don't see how dividing that by cos(x) now accomplishes anything? where...
  25. R

    Dot product vector question

    Homework Statement i'm having troubles solving this problem in physics involving dot product rule Vector B is 5m and 60 degress above the x axis A has the same magnitude as C and C is has 25 more degrees than A .. find magnitude of A.. B dot C = 35 B dot A = 30 this all we're...
  26. R

    Apparently easy Chain Rule Problem

    so i finally arrived at the solution thanks a bunch.. i justt needed to know if i was wrong right off the bat or if it was in my expansion and you jeez.. after awhile of work i found where i made my error.. and i arrived at \frac{d}{ds}F(s) = 3(s^2 - \frac{3}{s^4} + \frac{2}{s^7}) which...
  27. R

    Apparently easy Chain Rule Problem

    sorry for late response... the answer in the text is. \frac{d}{ds}F(s) = \frac{3( s^9 - 3s^3 + 2)}{s^7} when i expand i end up with something similar to yours but i obviously made an error somewhere I'm going to try again right now... i really don't see how they are arriving at this...
  28. R

    Apparently easy Chain Rule Problem

    Homework Statement F(s) = ( s - \frac{1}{s^2})3 I have to calculate the derivative of this using chain rule everytime i try i get something way different than in the back of the book... my first move is 3( s - \frac{1}{s^2})2 X ( 1 + \frac{2}{s^3}) is this correct? then expand...
  29. R

    Trig limit problem

    I am not familiar with l'hopitals theorem yet...
  30. R

    Trig limit problem

    Homework Statement is there a way to solve lim (x->0) \frac{x - sinx}{x^{3}} using the fact that sinx / x = 1 or is it much more complicated.. I've tried to break it down into sinx/x everyway i can think of with no luck..
  31. R

    Take the derivative of rational expression

    thanks I figured I could based on the rules... but I cannot see where I am making the mistake algebraically.. I'll rework again and post if i do not see the error of my ways
  32. R

    Take the derivative of rational expression

    Homework Statement f(x) = \frac{x}{x-1} + \frac{x+1}{3x} Homework Statement need to take the first derivative of this expression... I can do it but I am curious as too why i cannot take the derivative of \frac{x}{x-1} and then just add it to the derivative of \frac{x+1}{3x}...
  33. R

    Ration Inequalities Rule

    thanks for the excellent explanation!
  34. R

    Ration Inequalities Rule

    Homework Statement Quick question on Rational Inequalities.. Say I have \frac{1+x}{1-x} \huge\geq 1 Why can we not multiply 1 by denominator (1-x) is this because if x > 1 then (1-x) would be negative in effect changing the sign of the inequality.. but if x<1 then the...
  35. R

    Stuck on a possibly simple trig limit

    excellent thanks for your help!... i did look in the textbook again to confirm the answer and i see its showing a +infinity?? not sure what the reasoning behind the positive is? but fighting with this question has actually helped me understand a bit deeper. thanks!
  36. R

    Stuck on a possibly simple trig limit

    but in that form it just purely does not exist am i right? unless you know wether you're approaching zero from the right or the left.. you can end up with -infinity or +infinity... so it would need to be a one sided limit.. or am i off?
  37. R

    Stuck on a possibly simple trig limit

    that was exactly what i was doing wrong.. thank you very much it becomes forgive my poor latex.. I am trying 2 / sint/t - t/t sorry ill have to figure out better latex tomorrow but if I am correect that is 2 / 1 - t/t and since t/t is approaching zero but...
  38. R

    Stuck on a possibly simple trig limit

    yes I'm aware of sinx/x = 1 and all the other variations of it etc that's what i was referring to as the fundamental trig limit but i think its the fact its in the form. sinx - x i cannot factor out an x and since its in the form of a binomial this is where i think I am just doing something...
  39. R

    Stuck on a possibly simple trig limit

    Homework Statement how do you go about solving the equation lim (t->0) 2t / (sin(t)) - t the answer in the text is significantly different than what i get.. i can get most of the other trig limits using the fundamental limit etc.. but this one I am stuck ? i may be way over...
  40. R

    More limits

    not familiar with that yet ...
  41. R

    More limits

    Homework Statement lim (x->0) of (x - Sinx) / x^3 Homework Equations The Attempt at a Solution I would like to know the proper route for analyzing that question... the text is saying i should end up with 1/6 ...however I'm not sure how they arrived at that answer ...
  42. R

    Lim sin(1/x) as x->inf

    Thanks very much yes maybe he was thinking of that. but here is the actuall email he sent out correcting himself... if anything it confused me more... does what he say hold true? " The application of the squeeze theorem that we did in class to lim(x->inf)sin(1/x)/x, was correct and gives the...
  43. R

    Lim sin(1/x) as x->inf

    Homework Statement lim (x->inf) sin(1/x) i have a teacher that seems to think this is equal to 1.. I don't see how this is correct as x approaches infinity 1/x aproaches zero... sin 0 = 0 right? or is this the wrong way of thinking? Homework Equations The Attempt at a Solution
  44. R

    Determine size of mirror

    Homework Statement Quick question I can visualise but not determine mathematically.. The question in my text says: Determine the MINIMUM size of a flat vertical mirror that a person 178 cm can see his whole image. It suggest that a ray diagram will help. The Attempt at a Solution...
  45. R

    Simple Forces Question

    Thanks very much for your help. My head feels so much better.
  46. R

    Simple Forces Question

    okay nice! that's logic I've been messing around with as well and it seemed everything was going good and then I thought...well if T1 and T2 are 90 degrees and have 0 horizontal component then we assume 89.999999 degrees etc... can the same not be said for the load pulling downward giving it a...
  47. R

    Simple Forces Question

    is this not a joint sum of forces (note T1 and T2 are separated for clarity, you can think of them as attaching to the same point)? sorry to keep bugging you on this one. I really want to make sense of it and have not heard the term joint equilibrium before but from what I gathered on what I...
  48. R

    Simple Forces Question

    very good answer thanks so much for looking at my problem... There was some clarification issues on my behalf but you covered each situation perfectly. The initial question I posted "attached to separate anchors" was misleading because i meant separate anchors for connection to a wall or...
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