An unstable particle is created in the upper atmosphere from a cosmic ray and travels straight down toward the surface of the earth with a speed of 0.99537 c relative to the earth. A scientist at rest on the earth's surface measures that the particle is created at an altitude of 40.0 km.

As measured by the scientist, how much time does it take the particle to travel the 40.0 km to the surface of the earth?

Question

Abbigail Dean

Physics

9 August, 22:49

An unstable particle is created in the upper atmosphere from a cosmic ray and travels straight down toward the surface of the earth with a speed of 0.99537 c relative to the earth. A scientist at rest on the earth's surface measures that the particle is created at an altitude of 40.0 km.

As measured by the scientist, how much time does it take the particle to travel the 40.0 km to the surface of the earth?

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Answers (1)

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Ellen Moyer · Answer 1

Velocity relative to earth =.99537 c

=.99537 x 3 x 10⁸ m / s

= 2.98611 x 10⁸ m / s

distance relative to earth = 40 km = 40 x 10³ m.

Time measured by scientist

= 40 x 10³ / 2.98611 x 10⁸

= 13.395 x 10⁻⁵ s

= 134 μs.