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 42 of 48.
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.
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).
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.
Abdus salam said:
7 years ago
Thanks a lot for all the given explanation.
Swati warang said:
7 years ago
What is relative speed, can you explain in simple terms?
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.
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).
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.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers