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Amr Morsi

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Posts posted by Amr Morsi

  1. First, I think that F(x) = -q gradΦ(x), not F(x) = -q divΦ(x), is the correct formula.

     

    Second, you have the potential energy of the charge, which when added to the kinetic energy, gives the total energy E, which is a constant. The last equation is function of dr/dt, d(theta)/dt and r. Another equation for theta is

     

    r^2 * d(theta)/dt=constant=a,

    this equation is analogous to conservation of angular momentum.

     

    Both differential equations can be solved to find r in terms of t. Try it yourself.

  2. It is impossible to have c dimensionless in any system of measurement. It will always be length/time. But sometimes, it is omitted, but, it is known implicitly that any velocity term is divided by c.

     

    Actually, I think that the reason the velocity of light has this value is two points:

    1. The system we use for measurement.

    2. It is a universal constant, exactly such as pi. Actually, it is composed of 2 universal constants (epsilon and mu; permittivity and permeability)where

    c=1/sqrt (epsilon*mu)

  3. What is meant by "gravitational potential energy is gravity source also" is that it is another manifistation (face) of the gravitational energy. The mass of the potential energy is still "M", icarus2.

     

    The only relation connecting it with mc^2 is the following relation, which can be deduced from SR (Special Relativity), neglecting GR effects:

     

    -GMm/r+gamma*mc^2=E

     

    Where E is the total energy of motion of m.

    This is equivalent to what swansont is saying.

  4. Since atoms in one molecule are not moving with respect to each other, then magnetic field will not affect the internal structure of the molecule.

     

    But, since the whole molecule is vibrating, then the magnetic field will make the polarized molecule to rotate, but, will not increase, nor decrease its velocity (because magnetic force is always perpendicular to velocity).

  5. It is not a must to have a star collapse in order to produce gravitational waves. They can also be produced from 2 masses rotating around each others. In general, gravitational waves are produced from any accelerating mass....... very similar to electromagnetic waves.

     

    It is also to be noted that when a star collapse into a black hole, this doesn't imply a transformation to energy, but it is contraction of mass over space.

    By the way, simple spherically-symmetric contraction of stars or expansion doesn't emit gravit. waves, as stated by Einstein.

  6. The R.H.S. of Eq. 2 is only a function in y, the rest are constants. So, differentiate it with respect to y, and then substitute a time with y=0 and another time with y=1/2. You will get 2 relations for the constants a'o and a'1/2 and thus get both in terms of ao.

     

    The same can be done with eq. 3.


    Merged post follows:

    Consecutive posts merged

    I think you will have to integrate Eq.1 and T00 with respect to y in order to get rid of the delta function present in T00. Integrate it from -epsilon to +epsilon and thus some term in G00 will vanish and then substitute with the constants-relations you obtained previously.


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    Consecutive posts merged

    If Eq. 2 is NOT differentiable at y=0, try to integrate the equation following it(containing a''), it is the origin of Eq. 2...... It will be easy to evaluate.:)

  7. If the potential is not a function of time (i.e. function of space only), then schrodinger equation will be solved by separation of variables, and the time function will be only a phase function (exp(-iE*t/hbar)).

    However, if the potential is function of time, then the solution will be more complicated and the maximum of the probability density function will be moving with time through space; which gives the analogy to motion in classical physics.

  8. For the former equation you wrote, integrate both sides and make the boundary conditions -Pi and phi. You will get 1+k*phi=T, i.e. phi=(T-1)/k.


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    Sorry for this error. Make the boudary conditions phi and pi+epsilon. And, you will get 1+k*(pi - phi)=T.

  9. When you use a potential function in time (such as step up or step down) the schrodinger equation may give you a collapsed wave function or a generated one. But, in general, Schrodinger Equation gives stationary states when the potential energy (V) is not function in time, and the solution is obtained by SOV Method.

  10. 1. The curl of the static gravitational field will not change with the velocity nor acceleration of the affected body but with those of the source mass, i.e. it will be dynamic gravitational field. This can be solved using General Relativity.

     

    2. B® is solved in the attached file for the example you give, just put acceleration equal to zero. Exact B® is given and then approximation is made. Time retardation effects mean the properties of the charge at the time the radiations reach a position P...... It is not an approximation.

     

     

     

    - With respect to radiation; the electron gets accelerated from the external field, and some energy goes to the kinetic energy of the electron (and change in the direction of the velocity) and a small portion goes to the field radiation.

     

    - According to uniformly moving charges frame of reference, the magnetic field will be zero, as the charges will be considered motionless, only there will be electric field.

     

    Gauss's law for magnetism is an associated law (since the right hand side is zero), it helps in adding to the other laws that the magnetis flux lines are continuous.

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