Reverse Definition and 310 Threads

  1. A

    Exploring the Reverse Twin Paradox: Predicting Age Differences at .6c Speeds

    HI My question is what would the outcome be if the twins started out in 2 ships traveling at uniform .6c relative to Earth and one of them then took her ship and traveled to Earth and back? Which twin would be older?
  2. A

    Exploring the Reverse Twins Paradox: A Hypothetical Scenario

    Reverse Twins paradox ? This may have come up before but I haven't seen it and don't know the answer. What if the twins started out in two ships moving together at relativistically significant velocity relative to earth. One of the twins then simply goes to Earth and back while the other...
  3. D

    Integral problem reverse order

    Integral problem "reverse order" Greetings, This is from an online homework question: Evaluate the integral by reversing the order of integration. \int^{1}_{0}\int^{8}_{8y} e^{x^{2}}dxdy Although, I fail to see how this works, if I switch the order I get...
  4. R

    Reverse triangle inequality for n real numbers

    I have been trying the proof of the reverse triangle inequality for n+1 real numbers: |x-y1-y2-y3-...-yn| \geq | |x| - |y1| - |y2| - |y3| - ...-|yn| | I know the proof of the reverse triangle inequality for 2 real numbers and the triangle inequality for n numbers. can somebody help ?
  5. R

    Finding reverse sat current of pn junction diode

    Homework Statement Determine reverse sat current of diode. To show and explain approach. Given-IV characteristics of diode and tabulated values for forward bias voltage from 0-0.8v and corresponding current values. Homework Equations At which point do I need to consider to find the...
  6. T

    Can Electric Fields Exist Without Magnetic Fields?

    faraday's law states that if there is a change in the magnetic flux inside a conductor, a potential is induced across the ends. Is the opposite also valid, i.e. if I have a current carrying conductor with a constant potential applied across the ends, will there be a change in the magnetic flux...
  7. E

    Can green plants reverse entropy?

    Entropy is said to always increase. But do not green plants reverse entropy? Seems to me that everything they do increases order, down to the molecular level.
  8. K

    Reverse of optical isomerism in a reaction

    Homework Statement when chiral 2-bromobutane reacts with aqueous hydroxide ions, the optical activity of the product is reversed. Suggest why the optical isomerism is reversed. The Attempt at a Solution i have no idea... but i don't know if the fact that the hydroxide ion will attack...
  9. D

    How do I reverse the pattern of a LED ligt?

    I have an ackward question. I've been trying to device a circuit to reverse the pattern of a LED. Let me give you a quick rundown of my situation and my goal. As it stands now. Imagine a an alarm system. When activated a LED is lit 24/7. When a switch is triggered the led will blink...
  10. S

    How can reversing current affect battery charging?

    i am connecting a wire to a battery and i pass current in wire and so battery will be charged.suppose if i change the direction of current then will the battery charge? i.e if i change the direction of current alternatively after some time? why i am confused is because of this? suppose if i...
  11. N

    What Reverse Potential Difference is Required to Stop a Current in a Photoelectric Cell with a Caesium Surface?

    Homework Statement The work function of caesium is 1.35eV. A photoelectric cell has a caesium surface and is illuminated with monochromatic light of wavelength 400nm. What reverse potential difference must be applied to the tube to just stop a current passing through it? Homework Equations...
  12. F

    Is the HP-12C the Most Expensive RPN Calculator?

    Is HP the only company that sells calculators with RPN? Why is the HP-12C so expensive? It doesn't look expensive. I was wondering if it was possible to get a small pocket calculator that used RPN that wasn't too expensive?
  13. L

    Carnot engine working in reverse poblem-

    Homework Statement A heat pump is used to heat a building. The outside temp is -5.0 Celsius and the temp inside the building is to be maintained at 22 Celsius. The pump's coefficient of performance is 3.8, and the heat pump delivers 7.54MJ as heat to the building each hour. If the heat pump...
  14. R

    Reverse Partition grouping problem

    In an Excel group someone connected with the Texas caucus gave this math problem> how to subdivide the following set of precincts into subsets so that there are a maximum number of subsets from this set with each subset of precincts totaling at least 180 votes. Since the caucus is this month it...
  15. L

    Reverse Diffraction Research: Latest Findings

    I am to give my first physics talk for a seminar class next week and I am looking for info on recent research done on the reverse diffraction phenomenon. Any links or thoughts would be appreciated. (Credible sources only please, as this is for a class).
  16. R

    Reverse Magnus Effect: Exploring Lift Force & RPM Relationship

    Hi, I was looking at the NASA website's FoilSim application (google it) and for spinning objects, there is a maximum rpm. I was wondering why there were maximum/restricted rpms, so I emailed a NASA guy with the question. He said that the FoilSim App was for middle school students and that...
  17. R

    Question about Reverse Magnus Effect

    Hi, I was looking at the NASA website's FoilSim application (google it) and for spinning objects, there is a maximum rpm. I was wondering why there were maximum/restricted rpms, so I emailed a NASA guy with the question. He said that the FoilSim App was for middle school students and that...
  18. Ivan Seeking

    Medical Can deep-brain stimulation reverse memory loss?

    http://www.independent.co.uk/news/science/scientists-discover-way-to-reverse-loss-of-memory-775586.html
  19. B

    Copies of the SIR6 gene help reverse aging

    So would more copies of the SIR6 gene help reverse aging or anything like that if it's possible that deletion of the SIR6 gene speeds up aging a large amount? How dangerous would it be to have more copies of the SIR6 gene? If the mitochondrial theory of aging is correct, is there a way to...
  20. P

    Unable to reverse system restore

    I'm using windows XP and I'm trying to reverse the system restore I just did. I've tried undoing it, but my comp just keeps saying its unable to undo the system restore. What do I do?
  21. T

    Help with reaction CO+NO2 = CO2 + NO and activation energy for reverse

    For the reaction CO+NO2 = CO2 + NO, the activation energy for the forward reaction is 135 Kj/mol of CO reacted. a) Determine the heat of the reaction...
  22. U

    Reverse Breakdown Voltage of a 1N4002 Diode

    http://img151.imageshack.us/img151/1953/51953732lu5.png In this case, is the reverse breakdown voltage at V = 0V since there is negative voltage?
  23. W

    Proving 5G in G-Max Reverse Bungee in NZ & SG

    1. there is such a reverse bungee machine called the G-max Reverse Bungee in New Zealand and Singapore. Basically it works by attaching a car to two stretched giant rubber bands, then releasing them from the ground, so that it rockets up (to 60m), quite like reversed bungee jumping. it claims to...
  24. L

    The enzyme reverse transciptase is critical for?

    4. The enzyme reverse transciptase is critical for? A. converting the RNA genome of a virus into the DNA form of the host cell. B. converting the RNA genome of a bacterium into the doble stranded RNA form. C. replacig the uracil with the thymine in DNA strands. D. replacing the broken...
  25. C

    Reverse diferentiation problem

    Homework Statement (x^2+3x-1)/x^4 the answer is,(-x^-1)-(3/2)(x^-2)+(1/3)(x^-3)+CHomework Equations Just reverse diferentiationThe Attempt at a Solution =x^2+3x-1+x^-4 =(x^3)/(3)+(3x^2)/(2)-x+(1/3)(x^-3+C) (1/3)(x^3)+(3/2)(x^2)-x+(1/3)(x^-3)+C I know i got the answer but somehow it is...
  26. A

    Proving the Reverse of Case 3 of the Master Theorem

    Homework Statement i am trying to solve this but in vain... i need some help or hints to solve the questions below Show that case 3 of the master theorem is overstated, in the sense that the regularity condition a · f(n/b) <= c · f(n) for some constant c < 1 implies that there exists...
  27. C

    Whats reverse electromagnetic force?

    hi can you please tell me what is reverse electromagnetic force? thankz!
  28. M

    Reverse Pitot Flow: Pressure Differential?

    "reverse pitot" if one reverses the direction of flow in a pitot measuring system (i.e the pitot tube doesn't face the flow), will there still be a difference in pressure between the pitot and static tube ?
  29. R

    Finding the Saturation Current of a photodiode in Reverse Bias

    Homework Statement I am trying to finish the equation, to compare it against a set of data so I can then find the accuracy of my results in relation to the equation: I(dark) = I(sat) * e(qV/kT) -1 I have the following data: Va - the applied (bias) voltage q kB - Boltzmann Constant...
  30. R

    Why do mirrors reverse left and right but not up and down?

    why do mirrors reverse left and right but not up and down? thank you very much. Ryan.
  31. M

    Wire Reverse between Life and Neutral

    Hi, I really want to know if there is a way to do detection whenever wire been reversed between Life and Neutral. Any opinion guys?:smile:
  32. C

    Reverse time dilation possible?

    I've become fascinated by the prospect of using reverse time dilation as a means to achieve a "holy grail" of computational power. I'm probably going to get knocked down by not explaining this right (I haven't studied SR yet) but please try and understand what I mean. If a computer was...
  33. M

    Nernst potential and reverse potentials

    I know the following ion/inside cell/outside cell Cl- 5mM 150 mM K+ 130mM 5mM Na+ 20mM 140mM Ca2+ 10^-4mM 2mM How would I find the reversal potential for conductance equally permeable to sodium and potassium? How do I find the reversal potential for a conductance equally permeable to...
  34. F

    Why Is 66 Added Instead of Subtracted for Reverse Reaction Ea?

    Hello everyone, Here's my question. We have a reaction with an overal enthalpy change of -66KJ. The activation energy is 7KJ. We want the Ea for the reverse reaction. Formula: Ea (rev) = ∆E + Ea (fwd) So I wrote: Ea (rev) = -66 + 7 = 59 KJ. But the corrected exercise says: 66+7 =...
  35. D

    Reverse Reactions: Standard Enthalpy & Thermodynamics

    If it is thermodynamically favored for a reaction to occur forward and reverse, does that mean that the standard enthalpy of the reaction is close to 0?
  36. marcus

    The Rise of Slime: Marine Evolution in Reverse

    http://www.latimes.com/news/local/la-me-ocean30jul30,0,7764272.story?page=1 "...In many places — the atolls of the Pacific, the shrimp beds of the Eastern Seaboard, the fiords of Norway — some of the most advanced forms of ocean life are struggling to survive while the most primitive are...
  37. J

    Can you reverse transform a thin film diffraction pattern?

    Thank you for your insights on this. Suppose our kitchen table has a double glass top. Here and there it produces Newton's rings type interference patterns. I understand that by reverse transforming an interference pattern you can recover an image. If I were to somehow do this...
  38. L

    Is it posible to reverse permntly polarity of a permanentmagnet?

    Im working at this at the moment on this and i was wondering if is posible to reverse polarity of a permanent magnet without expending huge ammounts of energy and keep that polarity
  39. marcus

    Johan Noldus: A Unique Perspective on Quantum Gravity

    Johan Noldus is an interesting "outsider" figure on the margins of QG. This thread (if he happens to come across it) will give him a chance to make himself visible to us and to discuss his approach to QG---which he asserts to be radically different from that taken by the other efforts to put...
  40. H

    Reverse Bits on Pentium-Class PCs: Assembly & C Functions

    Can some one guide me ,,how to write an assembly language function for Pentium-class PCs with the following features. 1. C callable. 2. Takes one 32-bit argument 3. Returns 32-bit argument obtained by reversing the bits of the input (i.e. bit 0 of input appears at bit 31, bit 1 at bit 30...
  41. A

    Reverse engineer a one-wire bus

    I built a computer in my car, mainly for navigation and mp3 purposes. I would like to display song/artist information to the OEM LCD screen. There is a one wire bus in a wiring harness that carries data (track name, artist name, XM channel) from the XM tuner to the LCD in the dash. I'm...
  42. L

    Is reverse time dilation posssible?

    Hypothetically, if someone built an antigravity generator out of an exotic material that warped spacetime in an opposite way, so that matter was repelled instead of attracted, would the passage of time speed up for that frame of reference? I'm not a physicist or physics student, though I am a...
  43. E

    Reverse Polarity: Understanding and Application

    So, we are just starting ABEL... and I don't quite understand reverse polarity usefullness or application. Here's the extract from my textbook (Wakerly, 3rd ed.): "In this example, the reverse-polarity equation has one less product term than the normal polarity equation (whatever...the...
  44. J

    Why doesn't a mirror reverse top to bottom?

    If a mirror reverses left to right, why doesn't it reverse top to bottom?
  45. B

    Temp Effects on Forward & Reverse Rate Constants

    What would be the effect of an increase in temp on the rate constant of a) the forward reaction b) reverse reaction and my second Q is..why is it important to specify the temp when giving a value for Ke? Thanks
  46. R

    Determine the activation energy for the reverse reaction

    Hey , I still do not understand how to determine the activation energy for the reverse reaction when you are given the activation energy for the forward reaction and the delta h for the reaction. I was told to draw an energy diagram but I think I am drawing it wrong. I do know that the...
  47. E

    Can Piezoelectric Crystals Generate Electricity Under Stress?

    Piezoelectric Crystal Vibrates When Subjected To An Electric Pulse , Now I Wonder If Putting Stress On A Piezoelctric Crystal Would Yeild An Electric Pulse ?? And If That Is So, Are There Any Machines Based On This Theory ?and If There Are ,how Efficient Are They ??
  48. N

    Solving the Force of Reverse Thrust on Mars' Polar Lander

    Hi guys… there was a lot of arguing in my class when my teacher gave us this one assignment question that I’m not too sure about. It goes as follows… A Polar Lander somewhere above the surface of the Mars is landing with a deceleration of 23m/s^2. If the Lander itself had a mass of...
  49. S

    Reverse engineering relativity?

    Is it possible to start with the Lorentz transformations - I mean the whole Poincare group SO(1,3) - and derive that there exists an invariant speed? Is this a known derivation? I suppose we could assume a "flat" manifold with metric Diag(1,-1,-1,-1,).
  50. M

    The game of reverse Tic-Tac-Toe, called Eot-Cat-Cit

    The game of reverse Tic-Tac-Toe, called Eot-Cat-Cit, has the same rules as Tic-Tac-Toe, except that the first player with 3 markers in a straight line looses. Can the player with first move avoid being beaten? (note: a tie counts as a win for player 1)
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