Question

Special relativity is famous for "train questions". There are always textbook questions about the length of trains passing through tunnels and platforms. So, to honor a century-long tradition of learning, we'll do one also. Imagine a train that is 400 meters long in its own inertial reference frame, and a railway platform is 320 meters long in its own inertial reference frame. The train speeds by the railway platform so fast that, in the platform's reference frame, both the train and platform are exactly the same length. How fast must the train be moving, as a fraction of c? Penalty factor 25% Select one: 0 a. 0.2 cross out b. 0.4 cross out O cross out c. 0.6 d. 0.8 e. none of the above cross out o cross out

Answer 1

Guven. In the rest frame of platform length of train , to = 4.00 m. Length of platform, L = 320 m. When train is moving with velocity vo the train length was seem to be the length of platform . Lo ri-v2 = L. $ 400 VI-Van - 320 & unr = 1-0.64 sv-Jo.36 a v= 0.6c & 0.6c. train is moving with velocity