At what speed would an object have to be traveling for its length to appear to a stationary observer to have decreased to 1/3 of its length when seen at rest? (c = speed of light)

Question

Quizplus · Accepted Answer

This is a question about the relativistic length contraction formula: L' = L/sqrt(1-v^2/c^2). Let L' be 1/3 of L. Rearranging and solving for v, we get v = sqrt(1-(1/3)^2)/(sqrt(1-(1/3)^2))c = 0.94c. Therefore, the correct answer is B.

At What Speed Would an Object Have to Be Traveling