1. Problems on Trains - Types of Problems
with Examples
Published on Wednesday, May 25, 2016 By - Unknown
Problems on Trains chapter is almost same as TIME AND DISTANCE. The
only difference is that the length of the moving object is also considered.
Some important things to be noticed:
(i) When two trains are moving in opposite directions, their speeds should be added to
find the relative speed.
(ii) When they are moving in the same direction, the relative speed is the difference of
their speeds.
(iii) When a train passes a platform, it should travel the length equal to the sum of the
lengths of trains & platform both.
Trains passing a telegraph post or a stationary man
1.How many seconds will a train 100 metres long running at the rate of 36 km an
hour take to pass a certain telegraph post?
Solution: In passing the post the train must travel its own length.
Now, 36 km/hr = 36 ×5/18 = 10 m/sc.
∴ Required time = 100/10 = 10 seconds.
Trains crossing a bridge or passing a railway station
2. 2.How long does a train 110 metres long running at the rate of 36 km/hr take to
cross a bridge 132 metres in length?
Trains running in opposite direction
3.Two trains 121 metres and 99 metres in length respectively are running
in opposite directions, one at the rate of 40 km and the other at the rate
of 32 km an hour. In what time will they be completely clear of each
other from the moment they meet?
Trains running in the same direction
4. In example above. If the trains were running in the same direction, in
what time will they be clear each other?
3. Trains passing a man who is walking
5. A train 110 metres in length travels at 60 km/hr. In what time will it pass
a man who is walking at 6 km an hour (i) against it; (ii) in the same direction?
Solution: This question is to be solved like the above examples 3 and 4, the only
difference being that the length of the man is zero.
6. Two trains are moving in the same direction at 50 km/hr and 30 km/hr. The
faster train crosses a man in the slower train in 18 seconds. Find the length of
the faster train.
4. 7. A train running at 25 km/hr takes 18 seconds to pass a platform. Next, it takes 12
seconds to pass a man walking at 5 km/hr in the opposite direction. Find the length of the
train and that of the platform.
Shortcut Trick for Problems based on
Trains Questions
Published on Tuesday, April 26, 2016 By - siva
First we need to know how to convert kmph to mps :
Example : Convert 72 kmph to mps ?
5. In traditional method we need to multiply 5/18 to 72
⇒ 72×5/18 = 20 mps
Here its seems to be easy but in problems speed is in fractions we face difficult.
Tricky method :
Here what ever the speed given in problem(fractions also) we just multiply with 10 ,
the resultant is how many meters it travel in 36sec , from this we can easily find out
" mps"
Example : Convert 14.4 kmph to "mps" ?
Multiply kmph with 10,it gives how many meters it travelled in 36 sec
⇒14.4 × 10 =144
⇒ 144 --------- 36
⇒ ? ---------- 1
From this cross multiplication we need to find 1 mps
⇒ 144/36=4 mps
How to Convert Mps To Kmph ? :
6. Similarly we need to know " how to convert "mps" to "kmph"
Example : Convert 4 mps to kmph ?
Here we need find out first how many meters it travelled in 36 sec
? ------ 36
4 ------ 1
= 144
Here we need divide with 10
= 144/10 = 14.4 kmph
Examples :
Ques 1.
A train is 100 meter long and is running at the speed of 30 km per hour. Find
the time it will take to pass a man standing at a crossing.?
Answer :
30×10 ------ 36
100. ------ ?
7. = (36×100)/(30×10) =12 sec
Ques 2.
A train is moving at a speed of 132 km/hour. If the length of the train is 110
meters, how long will it take to cross a railway platform 165 meters long.
Answer :
Total length need to cross train is 110+165= 275m
132×10 ------- 36
275 ------- ?
= (36×275)/(132×10) = 7.5 sec
Ques 3.
Speed of a goods train is 72 km/hr. This train crosses a 250 meter platform in
26 seconds. Then find the length of goods train.
Answer :
Platform length =250m
Here take " x " as train length total length train need to cross = ( x + 250)m
(72×10) ------ 36
(X+250) ----- 26
⇒ 36×(x+250) = (72×10)×26
⇒ x =270 m
8. Ques 4.
A train speeds past a pole in 15 seconds and a platform 100 meter long in 25
seconds. What is length of the train ?
Answer :
Take train length as " x "
Total length its need to cross in 26sec is = (26+x)
X ------- 15
(100+x)-----25
⇒ 25x = 1500+15x
⇒ 10x = 1500
⇒ x = 150m
Ques 5.
Two trains of equal length are running on parallel lines in the same direction at
46 km/hr and 36 km/hr. The faster train passes the slower train in 36 seconds.
The length of each train is
Answer :
here train lengths are equal
⇒ Take it as "x" , so faster train need to cross total length of two trains = x+x=
2x faster train crosses slower train in 36sec
9. ⇒ Trains are traveling in same direction , so relative speed is = 46 - 36 = 10kmph
⇒ 10×10 ------36
⇒ 2x -------36
⇒ 2X =100
⇒ x =50m
Note: By this method we can easily calculate without pen and paper .
