Recent content by DavidBektas

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    Red Shifts and the expanding universe

    That would imply that the redshift is either due to gravitational or velocity redshift, which leads to a big problem for large distances. If you interpret the redshift as the "common" Doppler-Shift, you would get velocities v>c for objects at large distances (plus, you would need to explain...
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    Red Shifts and the expanding universe

    GeorgeSol is right, the main factor for the redshift varies with distance: 1. For small distances the photon only travels a relatively short time and therefore the redshift due to the expansion of space is small as well. The main factor in this case is the velocity of the object. 2. For...
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    Last edited by a moderator: May 2, 2017

    Hey Hasman, you don´t necessarily need the density. Just insert the radius of the sun for the radius of the black hole in the above calculation and you are there! And I believe the calculation for the density is correct. Sorry for my english...
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    Last edited by a moderator: May 2, 2017

    I think you have to insert the Radius of the sun for r (look at the link). Thats why the formula is often given in the form d=R*(2D´/D)^1/3 so that you don´t need to know the radius of the satellite. Other than that it should be correct.
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    Challenging Math Problems for the Curious Mind

    Well, I have a problem which currently bugs me (although I think I already solved it). Find the solution to the differential equation: dv/dt = a*v+b*v^2. It represents the movement of a particle with a velocity dependent friction force (which is proportional to v for small v and...
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    Is a Heightfield a Scalar or a Vector and How Many Dimensions Does it Have?

    Hello Hexa, in the case of h=h(x,y) you get for each set of values x and y a corresponding height h, which is a scalar. Or to put it another way: For every point on the x-y-surface you get a certain height h. So altogether the function describes a 2-Dimensional surface in a 3-Dimensional...
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    Doppler Effect and the Expanding Universe

    Franznietsche is right. From Wikipedia: http://en.wikipedia.org/wiki/Redshift ... v > c is possible for objects dominated by cosmological redshift because the spacetime which separates the objects (eg a quasar from the Earth) is expanding and spacetime is described by general relativity...
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    What happens to the temperature of the gas?

    In the case of rapid expansion/compression you could use the adiabatic laws to calculate how the Temperature changes with Volume (without considering the pressure; all you need is the initial Temperature and the Volume before and after). Here´s a link...
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    Clear Up My Misconception: Magnet & Magnetic Force Work w/o Energy?

    I´m pretty sure that the potential is always a scalar. By definition, the Force resulting from a potential U is F = grad U, which would make no sense if U was a vector field.
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