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 12 of 48.
Amit said:
1 decade ago
Can any one tell me why we have mulipled 25/2 to 18/5..why it should not be multiplied by 5/18 and also how ?
x - 5 = 45 ....as I understand it should be 40 km/hr
x = 50 km/hr. Because x=45.
45-5=40....hence anyone pls clarify.
x - 5 = 45 ....as I understand it should be 40 km/hr
x = 50 km/hr. Because x=45.
45-5=40....hence anyone pls clarify.
Ragavan said:
1 decade ago
As from the problem. two contrain have to remember
*If the man moving towards train. so that train pass the man faster then speed so add the distance.
*If not move towards train. The train pass the man late.so minus the distance
*If the man moving towards train. so that train pass the man faster then speed so add the distance.
*If not move towards train. The train pass the man late.so minus the distance
Mamatha said:
1 decade ago
To convert km/h into m/s we multiply that value with 5/18.why is this because
1km=1000m
1h=60min*60sec=3600sec
now
1km/h=1000/3600=5/18
if we want to convert m/s into km/h we have to multiply with 18/5.
hope you can understand.
1km=1000m
1h=60min*60sec=3600sec
now
1km/h=1000/3600=5/18
if we want to convert m/s into km/h we have to multiply with 18/5.
hope you can understand.
Shashank shekhar said:
6 years ago
Train crossing a moving object without length in same direction:
Formula is :-
Time=length of train / ( speed of train-speed of object).
10 sec = 125 m/ ( x - 5*5/18).
So, x=125/9 m/sec = 125/9 * 18/5 km/h = 50 km/h.
Formula is :-
Time=length of train / ( speed of train-speed of object).
10 sec = 125 m/ ( x - 5*5/18).
So, x=125/9 m/sec = 125/9 * 18/5 km/h = 50 km/h.
(1)
Raghu k said:
4 years ago
It is simple guys.
If we observe hint, her there should be the relative speed because the train and are travelling in the same direction so we (train) -v (man) T =Distance.
(120/10) (18/5) =v (t) -5.
45+5=v (t).
50=v (t).
If we observe hint, her there should be the relative speed because the train and are travelling in the same direction so we (train) -v (man) T =Distance.
(120/10) (18/5) =v (t) -5.
45+5=v (t).
50=v (t).
(8)
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.
Omkar tanpure said:
7 years ago
Relative Speed = 45 km/h.
Speed of man = 5 km/h.
But, we know, here,
Relative speed = Speed of train - Speed of the man.
Therefore,
Speed of train = Relative speed + Speed of man.
So, Speed of train = 45 +5 = 50 km/h.
Speed of man = 5 km/h.
But, we know, here,
Relative speed = Speed of train - Speed of the man.
Therefore,
Speed of train = Relative speed + Speed of man.
So, Speed of train = 45 +5 = 50 km/h.
Sheela said:
1 decade ago
1km=1000m.
1hour=3600sec.
So to convert from km/hr to m/sec, we need to divide 3600/1000 i.e,.
1km/1hr=3600s/1000m which is equal to 18/5.
If it was asked to convert m/s to km/hr then it would be 1000m/3600s= 5/18
1hour=3600sec.
So to convert from km/hr to m/sec, we need to divide 3600/1000 i.e,.
1km/1hr=3600s/1000m which is equal to 18/5.
If it was asked to convert m/s to km/hr then it would be 1000m/3600s= 5/18
Aruntracer said:
1 decade ago
@Diksha.
A train 125 m long passes a man, running at 5 km/hr in the same direction means the , in between man and running is for confusing you it should be taken as 125 m long train passes a man running at 5 km/hr.
A train 125 m long passes a man, running at 5 km/hr in the same direction means the , in between man and running is for confusing you it should be taken as 125 m long train passes a man running at 5 km/hr.
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).
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