Imagine that we define the rear end of a train 120 m long to long to define the
ID: 2125595 • Letter: I
Question
Imagine that we define the rear end of a train 120 m long to long to define the origin X'=0 in the train frame and we define a certain track signal light to define the origin X=0 in the track frame. Imagine that the rear end of of the train passes this sign at t+t'=0 as the train moves in the +X direction at a constant speed of 25 m/s. 12 seconds later, the engineer turns on the train's heasdlight. A) Where does this event occur in the train frame? B) Where does this event occur in the track frame
Explanation / Answer
From the train frame.
The event occur at x = 120 m
12sec later distance travelled by train, d = 12*25 = 300m
So from track frame, the event occur at X = 300 + 120 = 420 m