Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 9)
9.
Two trains are moving in opposite directions @ 60 km/hr and 90 km/hr. Their lengths are 1.10 km and 0.9 km respectively. The time taken by the slower train to cross the faster train in seconds is:
Answer: Option
Explanation:
Relative speed = (60+ 90) km/hr
| = |  |
150 x | 5 |  m/sec |
| 18 |
| = | |
125 | m/sec. |
| 3 |
Distance covered = (1.10 + 0.9) km = 2 km = 2000 m.
| Required time = | |
2000 x | 3 | sec = 48 sec. |
| 125 |
Discussion:
107 comments Page 3 of 11.
Sarang said:
7 years ago
Distance =speed*time,
1.10+.9=60+90*time,
2km=150km/h*time,
2000=150*5/18*time,
2000=750/18*time,
2000=41.66*time,
2000/41.66=time,
Time=48 s.
1.10+.9=60+90*time,
2km=150km/h*time,
2000=150*5/18*time,
2000=750/18*time,
2000=41.66*time,
2000/41.66=time,
Time=48 s.
(1)
Tarek said:
7 years ago
Then the time taken by the faster train to cross the slower will be?
(1)
Hsu Hsu said:
6 years ago
Why do you sum the relation speed of the train in the opposite direction?
If direction are same, will you sum?
Please, someone, explain to me, I need help!
If direction are same, will you sum?
Please, someone, explain to me, I need help!
(1)
Nandy said:
2 decades ago
Time=length/speed
required time=(2000/(125/3))
which is equal to=2000*(3/125)
required time=(2000/(125/3))
which is equal to=2000*(3/125)
CHANDRU said:
2 decades ago
Train moving in opposite direction why are you adding?
Deepti said:
2 decades ago
In opposite direction speed are summed up and in same direction speed are subtracted.
Jyoti said:
1 decade ago
How can you know it is the speed of the slower train?how the time taken by the faster train be calculated?
Arun said:
1 decade ago
@jyoti :90>60 so train wit speed 60 s d slower train.. V need not calculate d speed of d faster train.. It can be done using d formula a+b/u+v... Where a is d distance trav by faster train and b s dat of slower..u and v r d speeds of faster and slower trains
Pavan said:
1 decade ago
Hi arun great job.
Raj said:
1 decade ago
Use simple formula :
1)if 2 things acts in same direction( may be 2 trains or train&jogger)
time they meet t=(x+y)/(u-v)
where x,y-distance of trains or something
u,v-speed's in mps.
2)if 2 things acts in opposite direction:
time they meet t=(x+y)/(u+v)
1)if 2 things acts in same direction( may be 2 trains or train&jogger)
time they meet t=(x+y)/(u-v)
where x,y-distance of trains or something
u,v-speed's in mps.
2)if 2 things acts in opposite direction:
time they meet t=(x+y)/(u+v)
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