Multiple choice

The length of a train is 1 km. It entered into a 1 km long tunnel at the speed of 1 km / min. How much time it will take to cross that tunnel ?

  1. 1 hour

  2. 4 minutes

  3. 1 minute

  4. 2 minutes

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

For a train to completely cross a tunnel, it must travel distance = train length + tunnel length = 1 + 1 = 2 km. At 1 km/min, time = 2/1 = 2 minutes. The train enters at t=0 and exits at t=2.