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Concepts Of Physics MCQ Edition [Volume 2]PhysicsThe Special Theory of Relativity

Before decaying, a specific particle produced in a nuclear reactor leaves a 1 cm track. Determine the life of the particle in the frame of the particle, assuming it travelled at 0.995c .

Options

  1. A3.35 ps
  2. B335 ps
  3. C3.35 ns
  4. D33.5 ps

Correct answer

A. 3.35 ps

Step-by-step solution

The distance travelled by the particle in the laboratory frame is L = 1 cm = 10⁻² m . The speed of the particle is v = 0.995c . The time lived by the particle in the laboratory frame is given by: t = L v = 10⁻² 0.995 3 10^8 = 10⁻¹⁰ 2.985 33.5 10⁻¹² s The life of the particle in its own rest frame (proper time t₀ ) is related to the laboratory time by time dilation: t = t₀ 1 - v^2 c^2 t₀ = t 1 - v^2 c^2 Substituting the values: t₀ = 33.5 10⁻¹² 1 - (0.995)^2 t₀ = 33.5 10⁻¹² 1 - 0.990025 t₀ = 33.5 10⁻¹² 0.009975 t₀ 33

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