Recent content by ppzmis

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    What is the derivative of the square root of 2x using the chain rule?

    I just wanted to be clear that the square root applied to the 2 and the x and not just the x hence the brackets
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    Thermodynamics, first law, pressure increase, volume increase

    pV/T = const const pressure: 1/(27+273) = 3 / (T + 273) --> dT = 600 Q1 = mc_v dT = 0.01kg * 908 * 600 = 5448 KJ const vol: 1 / (627 + 273) = 2 / (T + 273) --> dT = 900 Q2 = mc_pdT = 0.01kg * 653 * 900 = 5877 kJ Q_total = Q1 + Q2 = 11325kJ
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    Deriving Moment of inertia for a hollow sphere

    Easier just to point to a link than write it out http://cnx.org/content/m14292/latest/
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    Variability of the speed of light

    I've measured it!
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    What is the Force of Friction on a Block Being Pulled at Constant Velocity?

    what is Newton's 1st law? Be worth having a think about it
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    What is the derivative of the square root of 2x using the chain rule?

    So long as your answer is (2x)^(-1/2) not 2*x^(-1/2) then you are correct and the solution is wrong.
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    Where do all the interfered photons go?

    As I tried to explain above interference is a property that is relevant to the wave properties of light. If you are visualising an experiment with particle like photons these will not interfere. This is demonstrated by the experiments I describe. If not then these are like waves and you cannot...
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    Where do all the interfered photons go?

    with 2 pinholes you get an overlapping ripple pattern of two circles just like when you drop two pebbles in a lake. I don't understand what you are asking in the last half of this question
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    Where do all the interfered photons go?

    The phase shift at the slits is not important what matters is the phase shift between the waves passing through each slit at the point at which they are superposed. You add the electric fields of the waves at this point and square it to give you the intensity. Hence at certain points where the...
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    ** Question related to Orbital speed of star, Keep getting *10^4 to high?

    My thought was that the time period of the wobble is related to the planet moving around the star but both star and planet must orbit around the centre of mass with the same period. Otherwise if you think about a star and planet orbiting around a point in space you could end up with the...
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    ** Question related to Orbital speed of star, Keep getting *10^4 to high?

    so distance of star from com as you say is r= 6.33E8. period of orbit = 9.2E7 Circular orbit is 2.*pi. r/T = 43ms^-1
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    Temperature change in pipe of flowing gas

    I have a pipe with a constant mass flow rate dm/dt of air being blown gently through which opens out into the atmosphere at both ends. At the middle point of this pipe it is heated at a constant rate dQ/dt. Assuming that the air is heated rapidly and all the heat is transferred to the gas is it...
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    Walk on Wet Sand: Sun & Heat Causes Drying

    >Firstly I note this is an old thread, so why resurruct it? I found it by googling and no one had actually answered the question so why not. Why do people get so uptight about this just ignore it if it bothers you. >Secondly the answer is given in any (good) book of soil mechanics. Yes most...
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    Walk on Wet Sand: Sun & Heat Causes Drying

    Hi all, ignore all the answers given above they are all wrong! The phenomenon being described is called "Dilatancy" and was discovered by Reynolds about 100 years ago. It works only when you have well compacted sand that contains just enough water to cover all the individual grains. When you...
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