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A train travels at a constant speed of 120 meters per second. The front of the train has just reached the entrance of a tunnel. Two seconds later, all of the train is inside the tunnel, and 3 seconds after that, the back of the train exits the tunnel. What is the length of the train divided by the length of the tunnel? 

 Apr 1, 2020
 #1
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train takes 2 seconds to fully enter the tunnel      it still takes one more second for the front of train to reach the exit....and another two seconds for the back of the train to exit the tunnel

 

 

let's say it is travelling at 100 m/s

 

2 seconds to enter fully  =   2 s x 100m/s = 200m     this is how long the train is

3 seconds later the back of the train travels  300 m    and exits the tunnel      tunnel length = 300 m

 

length of train / length of tunnel   =   200/300  =   2/3

 Apr 1, 2020
 #2
avatar+23699 
+1

Wow...I just saw the speed of the train was given as 120 m/s

 

then   2 seconds to fully enter =  240 m train length

           3 seconds for back of train to exit = 360 m tunnel length

 

240/360 = 2/3     (same answer...I just wanted to use the given numbers)  cheeky

ElectricPavlov  Apr 1, 2020

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