Apion has a rest energy of 135 mev. it decays into two gamma ray photons, bursts of electromagnetic radiation that travel at the speed of light. a pion moving through the laboratory at v = 0.98c decays into two gamma ray photons of equal energies, making equal angles θ with the original direction of motion. find the angle θ and the energies of the two gamma ray photons.

kepler used the data from tycho blahe (his mentor) to construct the laws of planetary motion.

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.