Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 15)
15.
A train 110 metres long is running with a speed of 60 kmph. In what time will it pass a man who is running at 6 kmph in the direction opposite to that in which the train is going?
Answer: Option
Explanation:
Speed of train relative to man = (60 + 6) km/hr = 66 km/hr.
| = |  |
66 x | 5 |  m/sec |
| 18 |
| = | |
55 | m/sec. |
| 3 |
 Time taken to pass the man = |
|
110 x | 3 | sec = 6 sec. |
| 55 |
Discussion:
35 comments Page 2 of 4.
Rashmi said:
10 years ago
Case 1: When they are in opposite direction.
Length of train in m = (Speed of train + Speed of man) in m/sec*time in sec.
Case 2: When they are in same direction.
Length of train in m = (Speed of train - Speed of man) in m/sec*time in sec.
110 m = (60 kmph + 6 kmph) * time (sec).
110 m = 66 kmph * time (sec).
110 m = 66*5/18 (m/sec) * time (sec).
Time (sec) = 110/18.333.
Time (sec) = 6 sec.
Hint: To convert km/hr = m/sec multiply by 5/18.
To convert m/sec = km/hr multiply by 18/5.
Length of train in m = (Speed of train + Speed of man) in m/sec*time in sec.
Case 2: When they are in same direction.
Length of train in m = (Speed of train - Speed of man) in m/sec*time in sec.
110 m = (60 kmph + 6 kmph) * time (sec).
110 m = 66 kmph * time (sec).
110 m = 66*5/18 (m/sec) * time (sec).
Time (sec) = 110/18.333.
Time (sec) = 6 sec.
Hint: To convert km/hr = m/sec multiply by 5/18.
To convert m/sec = km/hr multiply by 18/5.
(1)
RPrabha said:
2 decades ago
Additive speeds are only valid for the objects moving in th esame direction. Here only difference is applcable. so the answer would be 7 sec approx.
(1)
Tarun said:
2 decades ago
Hey ramesh,
If you know the derivation please let us know.
If you know the derivation please let us know.
(1)
Manish said:
9 years ago
Guys why don't you'll go through the formulas given at the beginning of all the topic as this will clear most of the questions asked here at the beginning itself.
Priyavel said:
1 decade ago
hi friend
tarun
step 1) opposite direction so we add it(60+6)
step 2) we convert km/hour into m/sec so we multiply by 5/18
step 3)speed=distance/time
spep 4) time=distance/speed
i think now u get it clearly.
tarun
step 1) opposite direction so we add it(60+6)
step 2) we convert km/hour into m/sec so we multiply by 5/18
step 3)speed=distance/time
spep 4) time=distance/speed
i think now u get it clearly.
Chellem said:
1 decade ago
How it comes 5/18? anyone please reply.
Shanmu said:
1 decade ago
1 km=1000m
1 hour=3600 seconds
to convert from km/hour into m/sec
1000/3600=5/18 m/sec
got it !
1 hour=3600 seconds
to convert from km/hour into m/sec
1000/3600=5/18 m/sec
got it !
Arun said:
1 decade ago
hi.. can anyone just tell me why we r 55/3 as reciprocal to 3/55........? reply if u know....
Mini said:
1 decade ago
@Arun
speed=distance/time
time=distance/speed
speed = 66*5/18 [Converting km/hr to m/sec]
= 55/3 m/sec.
Therefore, time = 110/55*3
= 110*3/55
= 6 sec
i think u will understand now
speed=distance/time
time=distance/speed
speed = 66*5/18 [Converting km/hr to m/sec]
= 55/3 m/sec.
Therefore, time = 110/55*3
= 110*3/55
= 6 sec
i think u will understand now
Chetan said:
8 years ago
Why add 60km/hr+6km/hr there is not mention in question like both object move in parallel if they move in parallel, we can say add 60+6 but why here is use like this?
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