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  1. stevmg

    B Suspended Mass

    To maintain a 550 lb mass in the air not touching the ground at sea level (radius of Earth is 4000 miles), what is the expenditure of energy required given perfect efficiency of the process?
  2. stevmg

    Tissue transplantation

    How can one transplant a (donor) tissue to a recipient allograft and have it "take" if the donor and recipient are of different sex? They are automatically genetically different which can never be broached.
  3. stevmg

    The Safest Thing to Do On an Open Field During Lightning

    As in the the title, what to do if caught in an open field during a sudden lightning storm. Have heard conflicting recommendations from laying flat to squatting in two feet. Trying to avoid being part of the return strike which would not be pleasant at all.
  4. stevmg

    The Causes of Lightning

    This thread is to discuss the physics behind the causes/effects of lightning from a basic science point of view.
  5. stevmg

    NMRI electromagnetic principles

    In nMRIs the strong magnetic field plus the radio wave aligns protons. 1). Which protons? Just the proton ions (actually H3O+) from water; or protons in all molecules that contain hydrogen atoms such as water, fats, carbohydrates, proteins? 2). The relaxation phase does what? As the protons...
  6. stevmg

    The age old twin paradox

    Two twins A and (evil) B. Twin A remains "stationary" while evil B goes at near light speed to-and-fro. Ignoring General Relativity (acceleration/deceleration) evil B experiences time dilation and as result, when they meet up again, B's clock is behind A's clock. Look at it from B's point...
  7. stevmg

    Quick & Short Question on General Relativity

    A satellite orbiting the globe at some 300 miles at 18000 mph. Does the clock on the GPS tick slower or faster than the same clock on Earth? 1) the clock is distant to Earth and is under less gravitational pull, resulting in time slowing down less than the Earth clock, therefore ticks faster -...
  8. stevmg

    Magnetic Resonant Imaging Mechanics

    MRIs are used in medicine for diagnostic imaging. I am told it has something to do with protons. But in the human body protons don't exist, only occasional hydronium ions (H3O+. ) I am told that a strong magnetic field imparts a "spin" to the protons (I don't know if this in a quantum...
  9. stevmg

    Name of intermolecular forces of gases

    For a non-ideal gas expanding in a vacuum, the kinetic energy of each of the molecules does NOT remain consant as the gravitational effect of the other molecules would "slow down" these velocities by deceleration. What are those forces referred to? Are they "Newton" forces or what? I can't...
  10. stevmg

    Elliptical Orbits (Using Newton's Model)

    1) Is it theoretically possible in a universe of two planetary objects - a Sun in a fixed position and a planet of any other finite mass, for that planet to orbit the sun in a perfectly circular orbit (not an ellipse?) 2) Are the elliptical (or near elliptical) orbits that occur in the real...
  11. stevmg

    Electron field

    It is stated that electrons orbit the nuclei of atoms not as particles. By the Heisenberg Uncertainty Principle (whatever that is) one cannot pinpoint their actual location and one cannot track the motion of an electron as it orbits the nucleus. What is that all about? Please use 10th...
  12. stevmg

    Mercury's Precession

    Einstein used General Relativity to explain the aberrant precession of the planet mercury in its orbit around the Sun and was shown to be correct. What the dickens , in 10th grade English, does the "precession of mercury" mean?
  13. stevmg

    Are photons packets of electronic waves such as this below

    Are photons packets of electronic waves such as this below ----------\/\/\/\/\/\/\/\/\/-------------------------------------\/\/\/\/\/\/\/\/\/\/--------> Imagine the "------------------------->" line is an electronic beam.
  14. stevmg

    Definition time

    This is a continuation of the thread Derivation of proper time of acceleration in SR We have definitions for proper time, proper speed, proper acceleration, coordinate speed, coordinate time, and coordinate acceleration. 1) What is the definition ofproper distance? 2) If proper...
  15. stevmg

    Derivation of Hyperbolic Representation from Lorentz/Minkowski equations in SR

    This is a carryover from a previous thread: https://www.physicsforums.com/showpost.php?p=2875138&postcount=68 Sports Fans: I am familiar with the Minkowski equations and the Lorentz transformations in one or two dimensions: A) In algebraic form (1) t2 - x2 = t'2 - x'2 (2) t' =...
  16. stevmg

    Derivation of proper time in acceleration in SR

    To yuiop: Consider an object of mass m0 which, subjected to a constant force, accelerates at a0 initially. Initially, the velocity of this mass is zero but then picks up as this force is applied. By the relativistic momentum equation, a = dv/dt = a0\sqrt{(1 - v^2/c^2)}...
  17. stevmg

    Another Integral

    Homework Statement Sove the differential equation below. Limits, t= 0 to t \rightarrow \infty Homework Equations a0 is a given value (say, 9.8 m/sec2) at t = 0 dv/dt = a0\sqrt({c^2 - v^2/c^2}) The Attempt at a Solution sin-1(v/c) = a0t/c v/c should go from 0 to 1. My...
  18. stevmg

    Stargazing Velocity of shadow of solar eclipse

    If a solar eclipse is visible near the equatorial region on the Earth, does it move from West to East at about 1000 miles/hr?
  19. stevmg

    The Moon 's moon

    On August 27 we are supposed to see Mars adjacent to the Moon about 1 - 2 AM so it looks like this picture. Doesn't make sense. Mars is 37 million miles away while the moon is 1/4 million miles away. That makes the subtended arcs in a 75:1 ratio Moon:Mars (because Mars is twice the diameter...
  20. stevmg

    Medical UCLA Department of Psychiatry

    UCLA Study - latest news - important! A study conducted by UCLA’s Department of Psychiatry has revealed that the kind of face a woman finds attractive on a man can differ depending on where she is in her menstrual cycle. For example: If she is ovulating, she is attracted to men with...
  21. stevmg

    Approaching Mirrors

    Say that two mirrors are 3 ltyr apart and perfectly facing each other. Say they approach at 0.6c (relative to a "stationary" observer) M1---------------->0.6 0.6<----------------M2 If a lightbeam is flashed at M1 towards M2 and bounces back and forth until the mirrors cross each other...
  22. stevmg

    Minkowski Equation - II

    kev - From your prior post you brought in this URL: http://hubpages.com/hub/Minkowski-Diagram which has this diagram (figure 3) Using his v = 0.6c, how do you prove that the (1,1) is the same as the (2,2) I can't make it happen. Also, his Lorentz and Inverse Lorentz...
  23. stevmg

    The Minkowski equation

    The standard Minkowski 4-space equation runs like this (as far as I know); x'2 + y'2 + z'2 - c2t'2= x2 + y2 + z2 - c2t2 For purposes of simplicity, if we drop the y and z components and go to a 2-space, let c = 1 and x measured in units of c (if we express c as 300M m/sec, the 1 unit for...
  24. stevmg

    Acceleration/Deceleration in SR

    I just found out that you can do acceleration/deceleration problems in SR. I didn't know that. The problem I was thinking of was the classic Terence/Stella problem of recent fame on this Forum. See this post by Jesse M who solves this for constant velocities...
  25. stevmg

    Acceleartion and the laws of relativity

    Homework Statement a) When a frame of reference undergoes acceleration/decelation (whatever,) what happens with regards to the Lorentz equations and Simple Relativity? How do the equations "change?" b) It is said that when twins move apart (or clocks move apart) that this is a...
  26. stevmg

    Events can be simultaneous in one time frame but not so in others

    A recent forum thread went into a long disussion of simultaneity. The term "ansible line" was used (later referred to as a "simultaneity line.") Einstein demonstrated with a thought experiment with regards to lightning and a moving train that events can be simultaneous in one time frame but...
  27. stevmg

    Sadi Carnot

    This chain was "lost" in a previous thread and disappeared into the ionosphere. The question was based on the principle expounded in 1828 by Sadi Carnot (1796 - 1832) - some French military physicist and engineer - died kind of young.). I never knew the man. W = efficiency as a fraction of...
  28. stevmg

    Closure Speeds

    Using drudkh's example cited above and using Einstein's velocity addition formula, closure speed between a particle moving to the right at v and light coming from the right and moving left at c would still be c. Why? Let's use v as the velocity of the particle expressed as a fraction of c...
  29. stevmg

    Derivation of an old-time formula

    In certain physics textbooks, one starts with the assumption (in a one linear and one time dimension) that 1) x2 - c2t2 = x'2 - c2t'2 I don't want to go into that. Let us start from there. Now, if you assume that 2) x = vt, then 3) x' = 0 always because the origin is moving at...
  30. stevmg

    What does this mean?

    x_2=v*t. I was told that this is incorrect but I don't even know what it is. The Lorentz equations are: x' = \gamma(x - vt) t' = \gamma(t - vx/c2) How would you write that in matrix format?
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