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.
Farheen said:
7 years ago
To convert km/hr to m/sec we multiply it with 5/18.
If we are converting m/sec to km/hr we multiply it 18/5.
If we are converting m/sec to km/hr we multiply it 18/5.
Dhivya said:
7 years ago
L(train) = (speed of train-speed of object) * time.
125m = (St-5)km/hr * 10s,
112.5 * 18/5 = st - 5,
St = 50km/hr.
125m = (St-5)km/hr * 10s,
112.5 * 18/5 = st - 5,
St = 50km/hr.
Akeer said:
7 years ago
@Ganesh.
The Relative means related to speed. The two trains are in which direction moving based on that we have to take the speed to add or sub.
The Relative means related to speed. The two trains are in which direction moving based on that we have to take the speed to add or sub.
Ramu nayak said:
7 years ago
Relative velocity is nothing but the velocity of body A to body B.
Case 1:
A and B moving in the same direction
Vr= Va-Vb. (Va>Vb)
Vr= Vb-Va (VB>Va)
Case 2:
A and B moving in opposite directions.
Vr=Va+VB. (Velocity not matters).
Case 1:
A and B moving in the same direction
Vr= Va-Vb. (Va>Vb)
Vr= Vb-Va (VB>Va)
Case 2:
A and B moving in opposite directions.
Vr=Va+VB. (Velocity not matters).
Ganesh said:
7 years ago
Anyone please explain about relative speed.
Ganesh said:
7 years ago
They asked the train speed; but why we have to take relative speed?
Please tell me.
Please tell me.
Swati warang said:
7 years ago
What is relative speed, can you explain in simple terms?
Abdus salam said:
7 years ago
Thanks a lot for all the given explanation.
Rohit said:
7 years ago
Whenever we have to convert seconds or minutes to an hour then multiply by 18/5 and if to do vice versa then 5/18.
Jola M said:
7 years ago
Converting km/hr to m/s is x*5/18 (For eg, 36 km/hr means 36*5/18 =10 m/s).
Converting m/s to km/hr is x*18/5 (For eg, 10 m/s means 10*18/5= 36 km/hr).
Converting m/s to km/hr is x*18/5 (For eg, 10 m/s means 10*18/5= 36 km/hr).
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