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
- A3.35 ps
- B335 ps
- C3.35 ns
- 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