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    p=mv

    a photon is massless so m=0, therefore p=0?
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    well, you're truely stupid.

    if p = m, then x = s which equates to the compression of t, which renders l. Now, when l = t + (s - x) / p = m.

    geesh.. read a book once in a while?
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    (Original post by student438)
    p=mv

    a photon is massless so m=0, therefore p=0?
    Energy mass equivalency.
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    (Original post by j0rd4nn)
    well, you're truely stupid.

    if p = m, then x = s which equates to the compression of t, which renders l. Now, when l = t + (s - x) / p = m.

    geesh.. read a book once in a while?
    wow... yeah, i'm stupid... because i'm clearly saying p=m... rather than p=mv and p=0 because (0)v =0....
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    It's to do with the fact that essential everything comes down to energy.

    If you takes planks relationship

    E=hf and the fact that c=fl (where l is lambda = wavelength)

    Rearranging gives f=c/l

    Substituting into the first equation gives

    E = hc/l => E/c = h/l

    The units of energy/velocity reduce to kg.m/s which is momentum.

    Thus for a photon of wavelength l

    p = h/l
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    That is correct for classical physics, but at speeds close to the speed of light it becomes obvious that the relation p=mv is just an approximation. At these aforementioned speeds it becomes apparent that something needs only energy/ velocity to have momentum.
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    momentum p= mV
    photon energy is E = hf
    when photon is travelling its energy is equal to kinetic energy
    E= 0.5mV^2 rearrange to obtain photons mass
    use mass and velocity to find photons momentum

    but photon is travelling too fast so momentum formula is not very accurate
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    (Original post by j0rd4nn)
    well, you're truely stupid.

    if p = m, then x = s which equates to the compression of t, which renders l. Now, when l = t + (s - x) / p = m.

    geesh.. read a book once in a while?
    Trololololol

    OP, remember that energy and mass are interchangeable.
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    (Original post by j0rd4nn)
    well, you're truely stupid.

    if p = m, then x = s which equates to the compression of t, which renders l. Now, when l = t + (s - x) / p = m.

    geesh.. read a book once in a while?
    What rubbish are you on about? At least troll properly. Dear me.
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    (Original post by Shmeiks)
    That is correct for classical physics, but at speeds close to the speed of light it becomes obvious that the relation p=mv is just an approximation. At these aforementioned speeds it becomes apparent that something needs only energy/ velocity to have momentum.
    relativistic momentum.
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    OK, some people have argued that p=mv is only valid for low velocities. This not true, P=mv is valid for all velocities and will give the correct value provided that the relativistic mass is used, which becomes more apparent at higher velocities.

    Now, the reason that a photon has momentum is because it has energy

    Energy of photon E=HC/L (let L stand for lambda, the wavelength, c the speed of light and H plank's constant),

    then by using Velocity = f.L , f = frequency, you get that:

    P = H/L , essentially this is because of the equivalency between energy and mass.
 
 
 
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