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177.

Problem 2.28 (R)

A meson is created in a high-energy collision of a primary cosmic-ray particle in the earth’s atmosphere 200 km above sea level. It descends vertically at a speed of 0.99c and disintegrates, in its proper frame after its creation. We have to find the altitude above the seal level observed from earth when it disintegrates.

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In its rest frame the life of meson is .

Its speed as observed from earth is 0.99 c. Its life as observed from earth will be

Distance travelled by the meson as observed from earth from the instant it is created to its disintegration will be

As the meson was produced at 200,000 m above the sea level, the altitude at which it disintegrates as observed from earth will be