ELECTROMAGNETISM & RELATIVITY - Chapter 8, Exercise 1 Solution ========================================================== Lorentz Factor and Time Dilation at 0.6c PROBLEM ------- A particle travels at 0.6c. Calculate its Lorentz factor, and then calculate how much time passes for a stationary observer if 5 s pass in the particle's own rest frame. SOLUTION -------- Step 1: Calculate the Lorentz factor. gamma = 1 / sqrt(1 - v^2/c^2) v/c = 0.6, so (v/c)^2 = 0.36 gamma = 1 / sqrt(1 - 0.36) gamma = 1 / sqrt(0.64) gamma = 1 / 0.8 gamma = 1.25 Step 2: Calculate the dilated time using delta t' = gamma x delta t. delta t = 5 s (proper time, in the particle's own rest frame) delta t' = 1.25 x 5 delta t' = 6.25 s ANSWER: The Lorentz factor is 1.25, and 6.25 s pass for the stationary observer while 5 s pass in the particle's own rest frame. ---- WHY THIS WORKS AS AN ANSWER At 0.6c, the Lorentz factor comes out to a clean 1.25 because 1 - 0.6^2 = 0.64 is itself a perfect square (0.8^2), a common choice in worked physics examples for exactly this reason. The result confirms the chapter's own central claim: time genuinely runs slower for the moving particle from the stationary observer's own perspective - 5 s of "particle time" corresponds to a longer 6.25 s of "observer time," a real, measurable 25% difference at this speed, smaller than the chapter's own 0.8c example (which gave a roughly 67% difference) since time dilation grows more dramatically as speed approaches c.