A train moves at speed 4c/5. A clock is thrown from the back of the train to the front. As measured in the ground frame, the time of flight is 1 second. Is the following reasoning correct? “The γ-factor between the train and the ground is γ = 1/√1 – (4/5)2 = 5/3. And since moving clocks run slow, the time elapsed on the clock during the flight is 3/5 of a second.”