## Time/Distance  III

Q1:

A train of length 150 m took 8 s to cross a bridge of length 250 m. Find the time taken by the train to cross a telephone post near the track?

Ans: Total distance traveled by the train for crossing the bridge=150+250 = 400 m

Speed of the train = 400/8 = 50 m/s

Time taken by the train to cross the telephone post=150/50 =3 s

Q2:

A train of length 200 m took 7 s to cross a bridge of length 500 m. Find the time taken by the train to cross a telephone post near the track?

Ans: Total distance traveled by the train for crossing the bridge = 200+500 =700 m

Speed of the train= 700/7    =100 m/s

Time taken by the train to cross the telephone post= 200/100 =2 s

Q3:

A train of length 200 m took 6 s  to cross a bridge of length 400 m. Find the time taken by the train to cross a telephone post near the track?

Ans: Total distance traveled by the train for crossing the bridge = 200+400 = 600 m

Speed of the train=600/6 =100 m/s

Time taken by the train to cross the telephone post=200/100 = 2 s

Q4:

Two trains are running in a parallel track on opposite directions.The  speed of the two trains are 29 km/h and 25 km/h respectively.They took 26 s to cross each other.If the length of one train is 200m, then find out the length of the other?

Note: If the trains are travelling opposite directions, add speed of the two trains to find the net speed. If both are travelling on the same direction subtract to find the net speed.

Ans: Here both trains running at opp. directions.So

Net speed of the two trains = 29+25

=54 km/h

=54 x 5/18 m/s

=15 m/s

Total distance to be traveled to cross each other(total length of two trains) = 26 x 15 =390 m

The length of the second train = total length of two trains - length of first train

= 390 - 200

= 190 m

Q5:

Two trains are running in a parallel track on the same direction.The  speed of the two trains are 77 km/h and 41 km/h respectively.They took 1 min 4 s to cross each other.If the length of first train is 350m, then find out the length of the second one?

Ans: Here both trains running on the same direction.So

Net speed of the two trains = 77- 41

=36 km/h

=36 x 5/18 m/s

=10 m/s

Time taken to cross each other =1 min 4 s =64s

Total distance to be traveled to cross each other(total length of two trains)=64 x 10 = 640 m

The length of the second train = total length of two trains - length of first train

= 640 - 350

= 290 m