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Amr Morsi

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Posts posted by Amr Morsi

  1. area=0.5*base*height=0.5*base*sqrt(S^2-(9.5)^2), where S is the length of the side.

     

    Then, d(area)/dt=d(area)/dS*dS/dt= 0.5*19*S/sqrt(S^2-(9.5)^2) * 2 ft^2/min

     

    At height=8 ft, S=sqrt(8^2+(9.5)^2) ft.

     

    Substitute with S in the rate of change of area , and you will get the result.

  2. 1. You will have to check the Left Limit for the variable x. It will be lim f(x,y)=xo*y

    2. Check the Right Limit for the variable x. It will be also lim f(x,y)=xo*y.

    3. Therefore, the Left Limit of f(x,y), as x tends to xo, is equal to the Right Limit.

    4. Repeat the previous, as y tends yo. And, you will get the same results.

    5. Then lim f(x,y), as (x,y) tends to (xo,yo), is equal to f(xo,yo).

     

    Note: There are some simple functions that can be considered continuous, unless it is required to prove so....... such as f(x)=x, f(x)=x^2.

  3. Sorry, another factor is remaining which is lim f(x), as x tends to infinity, exists and is equal to zero.

     

    And, we have the theorm "If a real-valued function f(x) is continuous on (0,infinity) and its limit, as x tends to infinity, exists (and is finite), then f(x) is uniformly continuous."

  4. But, as you said, Einstein Tensor depends upon the Metric Tensor, therefore the metric (which is sufficient to describe the spacetime curvature) is defined in The Einstein Field Equation. Then, the basic background of gravity is defined in " The Einstein Field Equation".

     

    It is, then, what is remaining, is the way that spacetime curvature is acting upon the mass situated at certain position.

  5. O.K...... I was talking like that because f(x,y) is obviously continuous,

    and lim f(x,y), as (x,y) tends to (xo,yo), is f(xo,yo).

    If you need an exact proof, then find the left limit which will be f(xo - epsilon , yo - epsilon). And, find the right limit which will be f(xo + epsilon , yo + epsilon). Then, since both are equal then the limit is found.

  6. How is gravitational energy not involved in Einstein Field Equation?!

    It is totally built upon the effect of Mass on the spacetime curviture, which in turns define gravity. Gravitational energy is implied in the Einstein Tensor in the Equation.

    But, don't forget. There is another part that is remaining which is "An object in a gravitational field follows the shortest distance between two points". It is completing the description of the gravitaional effect on masses.

  7. For sure, many of the properties you stated about energy waves are correct. But, there is a difference between Probability Wave and Energy Wave.

     

    PW is describing the probability of existence of a particle under certain potential. Of course, the particle has energy, but, it is the wave nature of the particle not the energy.

     

    Energy waves, however, can be described by the motion of mediators, which are particles with special specifications. And, I agree with you, these mediators can be described quantatively by Quantum Field Nature according to the properties of the source of the field.

     

     

    When gravitons interact with a mass, this doesn't imply a change at the source. But, as this mass is affected, its own field of cource changes (at a velocity of c).

  8. I think that Fnet is not zero, it is equal to -dp/dt; where p is the momentum of gases.

    Vdm/dt is an additional term due to the change of the total mass of the rocket. But, it is not the only effect on the acceleration.

  9. Substitute with 8*pi*Tmn instead of Gmn. And, then raise the index n. I think this will come very close to eq 2 and eq 3.

     

    Multiplying with gmn will make the equation loose its nature tensor...... It will be scalar.

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