A train travelling at a speed of 80 mph enters that is 2.5 miles long. The length of the train is 0.5 mile. How long does it take for all of the train to pass through the tunnel from the moment the front enters to the moment the rear emargoa?
(1) 2 minutes
(2) 2 minutes 30 seconds
(3) 2 minutes 15 seconds
(4) 3 minutes
(1) 1
(2) 2
(3) 3
(4) 4
EXPLANATION
Option 3
To calculate the time it takes for the entire train to pass through the tunnel, you need to consider the relative speed between the train and the tunnel. Since the train is moving into the tunnel, you have to take into account the additional distance it travels while the front of the train is entering the tunnel.
Let’s denote:
- Length of the tunnel as (T) (2.5 miles),
- Length of the train as (L) (0.5 miles),
- Speed of the train as (S) (80 mph).
The total distance the train needs to cover is (T + L). The relative speed between the train and the tunnel is (S), so the time ((t)) it takes for the entire train to pass through the tunnel is given by:
T= (T + L)/ S
T= (2.5 + 0.5)/ (80/60)
T= 2.25 mins i.e 2 mins 15 secs
Leave a Reply