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 7 of 48.
Sarah said:
1 decade ago
Hi I can't understand friends. What is this x-5 ?
Please anyone explain clearly.
Please anyone explain clearly.
Suganthan.M said:
1 decade ago
We need the speed of the train
we have only one clue about the train is 125m and 10s
speed=distance/time
(i.e)125/10= 12.5 m/s
but we need the answer in km/hr so convert it
12.5*(18/5)=12.5*3.6
=45 km/hr almost we got it
then about the direction, it is in same direction
Now the speed of the train as x,
because of same direction subtract it from x
x-5=45
x=45+5
x=50km/hr
we have only one clue about the train is 125m and 10s
speed=distance/time
(i.e)125/10= 12.5 m/s
but we need the answer in km/hr so convert it
12.5*(18/5)=12.5*3.6
=45 km/hr almost we got it
then about the direction, it is in same direction
Now the speed of the train as x,
because of same direction subtract it from x
x-5=45
x=45+5
x=50km/hr
Chetana said:
1 decade ago
Thanks frnd. I understand properly.
Gowthami said:
1 decade ago
Nice explanation from you frnds but ravi said that we had add that relative speed, I can't understand from his point of view.
Jitendra Prajapati said:
1 decade ago
Very good explanation by Suganthan.
Meera said:
1 decade ago
Thanks mr. Suganthan. Its really very nice to understand thanks:) ) ).
Shashank said:
1 decade ago
Hi. Please tell me why x-5 ?
Binod verma said:
1 decade ago
When two things are running in the same direction or opposite direction then we say that motion is in relative between them. So at first we find the relative motion and then find the speed of train.
If someone want to find out speed of man that are given in the question.
If someone want to find out speed of man that are given in the question.
Dhandapani said:
1 decade ago
Simple you can multiply 5*10.
5-a man running 5km/hr and the train reached in 10 seconds.
5*10=50km/hr.
5-a man running 5km/hr and the train reached in 10 seconds.
5*10=50km/hr.
Washeru said:
1 decade ago
Good expl. frm Rahuul
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