Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 23)
23.
Two trains are running in opposite directions with the same speed. If the length of each train is 120 metres and they cross each other in 12 seconds, then the speed of each train (in km/hr) is:
Answer: Option
Explanation:
Let the speed of each train be x m/sec.
Then, relative speed of the two trains = 2x m/sec.
| So, 2x = | (120 + 120) |
| 12 |
2x = 20
x = 10.
 Speed of each train = 10 m/sec = |
 |
10 x | 18 |  |
km/hr = 36 km/hr. |
| 5 |
Discussion:
38 comments Page 2 of 4.
Jack said:
1 decade ago
No need to find the relative speed because speed and length of the both train is same.
So, simply find the speed of single train.
120/12 = 10 m/s.
10*18/5 = 36 km/ph.
So, simply find the speed of single train.
120/12 = 10 m/s.
10*18/5 = 36 km/ph.
Shabi said:
1 decade ago
Length of the each (two) train 2X = 120m.
Therefore for single train, x = 120/2 = 60m.
Find the seconds for single train, 2x = 12sec.
So speed = 6 sec.
Result, speed = D/S, 60/6 m/sec, 10 m/sec.
Convert to km/hr.
10*18/5 = 2*18 = 36 km/hr.
Therefore for single train, x = 120/2 = 60m.
Find the seconds for single train, 2x = 12sec.
So speed = 6 sec.
Result, speed = D/S, 60/6 m/sec, 10 m/sec.
Convert to km/hr.
10*18/5 = 2*18 = 36 km/hr.
Irshad said:
1 decade ago
In option no units are given then why should we convert.
Srikanth said:
1 decade ago
Distance = 120 m.
Time = 2 sec.
Speed = distance/time.
So =120/12 m/sec.
Then our answer is in km/hr.
So (120/12)*(18/5).
= 36 km/hr.
Time = 2 sec.
Speed = distance/time.
So =120/12 m/sec.
Then our answer is in km/hr.
So (120/12)*(18/5).
= 36 km/hr.
Kuldeep singh said:
1 decade ago
Length of train = 120 m.
Time = 12 sec.
Speed = ?
Speed = distance/time.
S = 120/12.
S = 10 m/s.
S = 10*18/5.
S = 36 km/hr.
Time = 12 sec.
Speed = ?
Speed = distance/time.
S = 120/12.
S = 10 m/s.
S = 10*18/5.
S = 36 km/hr.
Joel said:
1 decade ago
Guys here, each train is travelling 120 m so total distance is 240 m.
Yogesh said:
1 decade ago
18/5 why & where command please clarify it?
VIDYASAGAR SHARMA said:
1 decade ago
How 18/5 comes?
Abhishek said:
10 years ago
@Vidyasagar and @Ygesh this answer is for you.
Speed = 10 m/s, but they are asking the answer in km/h, so you need to change it.
Now see, 1 m = 1/1000 km and 1 sec = 1/3600 hr.
So 1 m/s = 1/1000/1/3600 which means 3600/1000 = 18/5.
Therefore 1 m/s = 18/5 km/h.
I hope you got it. If not tell me I will explain in a much simpler way.
Speed = 10 m/s, but they are asking the answer in km/h, so you need to change it.
Now see, 1 m = 1/1000 km and 1 sec = 1/3600 hr.
So 1 m/s = 1/1000/1/3600 which means 3600/1000 = 18/5.
Therefore 1 m/s = 18/5 km/h.
I hope you got it. If not tell me I will explain in a much simpler way.
Souvanik said:
10 years ago
Question is speed of each train?
Length of each train is 120 m and speed is also same.
So Speed = Distance/Time.
= 120/12 m/s.
= 10 m/s.
= 10*18/5 km/hr.
= 36 km/hr [1 m/s = 18/5 km/hr].
Answer will be 36 km/hr.
Length of each train is 120 m and speed is also same.
So Speed = Distance/Time.
= 120/12 m/s.
= 10 m/s.
= 10*18/5 km/hr.
= 36 km/hr [1 m/s = 18/5 km/hr].
Answer will be 36 km/hr.
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