Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 2)
2.
A train 125 m long passes a man, running at 5 km/hr in the same direction in which the train is going, in 10 seconds. The speed of the train is:
Answer: Option
Explanation:
| Speed of the train relative to man = |  |
125 |  m/sec |
| 10 |
| = | |
25 | m/sec. |
| 2 |
| = | |
25 | x | 18 | km/hr |
| 2 | 5 |
= 45 km/hr.
Let the speed of the train be x km/hr. Then, relative speed = (x - 5) km/hr.
x - 5 = 45 
x = 50 km/hr.
Discussion:
475 comments Page 17 of 48.
Eric said:
1 decade ago
@Shafi.
This method is quite simple and explain the whole concept, thanks for the nice explanation.
This method is quite simple and explain the whole concept, thanks for the nice explanation.
Bikramjit said:
1 decade ago
1 km/hr -------------> 5/18 m/sec.
5/18 m/sec ------------> 1 km/hr.
1 m/sec -------------> 1/(5/18)km/hr = 18/5 km/hr.
25/2 m/sec -----------> (18/5)*(25/2) = 45 km/hr.
If train speed x km/hr, then (x-5)km/hr.
x-5 = 45.
x = 45+5.
x = 50 km/hr(answer).
5/18 m/sec ------------> 1 km/hr.
1 m/sec -------------> 1/(5/18)km/hr = 18/5 km/hr.
25/2 m/sec -----------> (18/5)*(25/2) = 45 km/hr.
If train speed x km/hr, then (x-5)km/hr.
x-5 = 45.
x = 45+5.
x = 50 km/hr(answer).
ESWARAN.P said:
1 decade ago
Here using x-5=45. Please explain?
Vaishnapriya said:
1 decade ago
Consider x as the train speed(which is to be determined). We know a relative speed formula in same direction,
(u-v).
Using the given data find out the relative speed i.e 45.
Now,
Relative speed = (train speed-5).
(u-v).
Using the given data find out the relative speed i.e 45.
Now,
Relative speed = (train speed-5).
Selvakum said:
1 decade ago
(u-v). Using the given data find out the relative speed i.e. 45.
SURESHBABU KASTURI said:
1 decade ago
If two things are at same speed in same direction.
We subtract that,
So right 125-5=120.
Wrong is 125+5=130.
We subtract that,
So right 125-5=120.
Wrong is 125+5=130.
Srinivas Rao said:
1 decade ago
If both things are in the same direction, then we have to do subtraction right but why we have to do it.
Sankar said:
1 decade ago
Man has traveled 13.8 m in 10 sec.
i.e 5km/hr = 1.38m/s.
1.38*10s=13.8m he has traveled in 10 sec.
So 125m train has passed 13.8m in 10 sec.
So speed of the train is 13.8m/s i.e 49.68km/hr = 50 km/hr.
i.e 5km/hr = 1.38m/s.
1.38*10s=13.8m he has traveled in 10 sec.
So 125m train has passed 13.8m in 10 sec.
So speed of the train is 13.8m/s i.e 49.68km/hr = 50 km/hr.
PRIYANKA SHARMA said:
1 decade ago
Hello friends,
If you want to convert m/s into km/hr then multiply with 18/5.
For example: 5 m/s = 5m/s*18/5 = 18km/hr.
If you want to convert km/hr into m/s then multiply with 5/18.
For example: 108 km/hr = 108km/hr*5/18 = 30m/s.
If you want to convert m/s into km/hr then multiply with 18/5.
For example: 5 m/s = 5m/s*18/5 = 18km/hr.
If you want to convert km/hr into m/s then multiply with 5/18.
For example: 108 km/hr = 108km/hr*5/18 = 30m/s.
Satish said:
1 decade ago
What is the need of taking 15/10 and explain how it came?
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