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:
478 comments Page 23 of 48.
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?
Akshay said:
1 decade ago
Why should multiply 18/5?
Deepak meena said:
1 decade ago
It's simple way.
We know that the speed of train is 125m/10s.
Then 125/10 = 25/2.
This is the speed of train in 1 second.
Now speed in 1 hr = 25/2*3600 = 45.
And men is going in 5km/1hr so speed of train is 50km/hr.
We know that the speed of train is 125m/10s.
Then 125/10 = 25/2.
This is the speed of train in 1 second.
Now speed in 1 hr = 25/2*3600 = 45.
And men is going in 5km/1hr so speed of train is 50km/hr.
Krish said:
1 decade ago
How to be solve this 25/2*18/5 = 45?
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