studiot

All those lines? Do you first understand that in Fortran you must 'declare the variables' and it is usual to collect all these together at the start for convenience? So lines up to the starred lines are just declarations. or Are you asking about the subsequent do loops ? If so what do you not understand about them?

I have avoided commenting in this thread till now but removing Scotland from the UK is akin to a man with body dysmorphic disorder having a sound foot amputated, and just as silly. We would be better getting rid of Cameron than Scotland.

Finally an answer of sorts but I'm sorry to invoke the old adage There's none so blind as those that won't see. I have enhanced the relevant sentence. I do not like holding discussion with those who declare "whatever you are going to say is irrelevant", without knowing what I actually want to say.

That's a lot of numbers, Joe. Would you like to say what they mean?

All light has the same identical velocity, c, in every inertial frame to every observer. You need to be careful identifying the photon as a particle that travels at c though.

Yes and no. A single observer cannot do this, from the doppler effect. For example there is no doppler effect for motion at right angles to the line of intersection or for two bodies that are not moving apart. The size of the doppler shift gives you a value of the relative velocity along a vector which is the common line of intersection. So if you have another observer (In 2D) or two more observers (in3D) you can use the three such lines to find the resultant velocity of the object. However the observers must be suitably placed to achieve any accuracy.

Some thoughts. Firstly I don't believe anyone has clarified what sort of mass we are talking about. Inertial mass?, Gravitational mass? , Effective mass? or any two from three or all three? Secondly Depending upon your choice this would affect many areas of Physics, for example taking inertial mass to zero would mean zero kinetic energy, zero momentum and zero pressure, even if the particles remained in motion. Taking gravitational mass to zero would mean zero (gravitational) potential energy. Thirdly those quantities that have negative exponents of mass in their dimensions would involve division by zero. For example specific volume, molecular collision rate, average and rms speeds, diffusion coeficients and the like.

So here is my method for my problem for comparison.

Read post#2 by fuzzwood again +1

Spyman did you have a method or did you just guess? Since this is a science forum it would be nice to also discuss strategies for solving these things (both Einstein's and mine).

For your information you mean a CRT or Cathode Ray Tube monitor, which consumes 80 - 120 watts in your size. Modern replacements are LCD at 40 watts and LED at around 20 watts. These two comparison sites may interest you http://www.sustainableit.com/should-i-replace-my-crts-with-lcds/ http://energyusecalculator.com/electricity_lcdleddisplay.htm

I did but I used the word universe to avoid the word frame. You are still dodging the question What is the location of the source of the lightning? The answer to this is all important.

Yes I realise it is not perfect, but different places in the Forum give different answers as to whether a member is online or offline. The main board seems to update before the threads. Anyway thanks for looking at my post.

No, No and no again. Why do you insist on changing Einstein's stipulations? Any fool can change the experiment so that it fails. So what. And why do you not want to hear (follow) the logic behind what Einstein actually specified? And why do you not want to answer the simple question I asked you as to the location of the source of the lightning?

I'm sorry imatfaal, but your solution is not valid. Third time lucky? As a matter of interest when I asked some engineers awhile back they tried a brute force and ignorance method (let the computer try every combination and filter). One reported 164 sets of matching numbers another reported 150 but neither picked out the one and only correct one. other wrong possibilities include 768 * 142 = 109056 762 * 132 = 100584

Did Einstein have a clock specified in his train experiment? Please point me to the reference.

I'm happy to do some (easy) maths with you as a reasonable presentation for distortion in a transistor can be made without Fourier series. However I would appreciate more full answers as this means quite a bit of work and I need to get the level correct. Here is a start, tell me if we can continue. First I will simplify my original equation by dropping the phase part. Also since I am considering specifically transistors my transfer function will be written in terms of an input voltage and a resultant output (collector) current. That is at any instant the collector current will be Ic = f(Vi) So consider a signal Vi= Vmsin(wt) , input to the transistor. If the transistor were linear then the output would be a first order or linear function of the input That is Ic = Iq + aVi Where the instantaneous output (collector current) equals a constant current (Iq) plus a variable current proportional to the instantaneous input voltage. (The constant current is called the bias or quiescent currrent of the transistor) a is the constant of proportionality called the transfer coefficient. So Ic = Iq + aVmsin(wt) So for linear operation the output is the input multiplied by a constant of proportionality. So there is no distortion. Now I showed the transfer curve curling over for non linear operation. The simplest such curve is second order or a parabola so let us assume that Ic = Iq + aVi + b(Vs)2 = Iq + aVmsin(wt) + b(Vmsin(wt))2 Where b is a second constant to be evaluated. = Iq + aVmsin(wt) + b(Vm)2sin2(wt) Since sin2(wt) = 1/2(1-cos2wt) Ic = (Iq + b(Vm)2/2) + aVmsin(wt) - b(Vm)2/2 (cos2wt) So the output collector current consists of the following three components A DC component equal to (Iq + b(Vm)2/2) An alternating fundamental componenet of frequency equal to that of the driving frequency with a peak value equal to aVmsin(wt) An alternating second harmonic component of a frequency equal to twice that of the driving frequency and of a peak value equal to b(Vm)2/2 If you can follow this so far we can continue this simple analysis of the harmonic distortion.

Le Repteux, Atomic or other clocks are irrelevent. Time measurement is not needed in Einstein's train experiment. So if we can stick to the original experiment details please, I will make the same offer I made to Robin in post#79 It really is very simple if you note down the correct sequence of events, without missing any out.

I don't understand the inconsistencies of the forum clock and find it a positive nusisance at times. For instance when I am replying in a thread and the poster I am replying to is noted as being online, I might expedite my reply for their benefit. Then I find that going back to the index/menus the poster was actually recorded as being offline a significant time before I posted so my rush was needless. Now I see the ridiculous situation where the poster of post#97 in this thread http://www.scienceforums.net/topic/85331-thought-experiments/page-5 Is recorded as being offline at 1.12pm although He is also recorded as posting at 1.14pm I wondered if this is to do with the fact that the thread is (partly) about time dilation?

Rectifiers will simply loose you half the signal Distortion can be filtered to some extent, but you would not want to do this at the power stage, further filters will also reduce wanted output. OK so you haven't yet done Fourier series. Do you understand feedback? I have roughed out some quick sketches to help. The first is a voltage transfer function, linear and non linear like a transistor or most amps. The second is what happens when you feed a pure sine wave into an amp with the non linear transfer function. You get a flattened sine wave out. You should plot for yourself a few points to see what happens. This is the best teaching aid.

Now we are getting somewhere. Your lecturer is correct. Think about a sine wave. This means that the instantaneous amplitude is continually varying and we have an instantaneous (voltage) amplitude Vinst = Vmaxsin (wt+p) I hope you understand this bit? So when the amplitude is say 0.25 volts the amplification factor is say 100. When the amplitude is say 0.5 volts the amplification factor drops to say 85 When the amplitude is say 0.75 volts the amplification factor drops even more to say 65. This means that different parts of even a simple sine wave are amplified by different amounts. So the result is not longer a true sine wave. I don't know if you have come across Fourier or Harmonic analysis yet? But essentially any continuous waveform can be expanded in a trigonometric series called a Fourier series. The original sine wave had only one term in this series - the fundamental. Harmonic distortion introduces additional terms which describe the distorted waveshape. So another description of harmonic distortion is that it introduces frequencies not present in the original.

One manufacturer used to call the perfect amplifier as "A piece of straight wire with gain". What did your lecturer say about distortion, of any type?

Glad you have the interest. You will certainly need to know all this before the end of an electrical engineering course. The more information about where you are coming from or your interest in a question the better will be the forthcoming answer. I was expecting further questions about my initial response.

Note I didn't say they were always present. Is this homework ie have you been asked to find out a list of distortions? I would look at Crossover distortion Intermodulation distortion Phase distortion Transient intermodulation distortion Other unwanted signals include Noise Hum Interference Other unwanted effects include Pumping/ motorboating Limiting/ clipping Inaccurate pre-emphasis/de-emphasis

Harmonic distortion occurs because the amplitude transfer function is (hopefully only slightly) non linear. The standard design method of reduction is to attempt to make the basic amplifier as linear as possible and then apply negative feedback. The user's method is to operate the amplifier with the volume at around the 45% to 75% of maximum. You should be aware that there are other types of distortion that are may need other countermeasures.