Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 7)
7.
Two trains of equal length are running on parallel lines in the same direction at 46 km/hr and 36 km/hr. The faster train passes the slower train in 36 seconds. The length of each train is:
Answer: Option
Explanation:
Let the length of each train be x metres.
Then, distance covered = 2x metres.
Relative speed = (46 - 36) km/hr
| = |  |
10 x | 5 |  m/sec |
| 18 |
| = | |
25 | m/sec |
| 9 |
 |
2x | = | 25 |
| 36 | 9 |
2x = 100
x = 50.
Discussion:
232 comments Page 21 of 24.
Md. Habibur Rahman said:
5 years ago
When we calculated relative speed, Why we calculate 2x?
Relative speed means a train will be static. Then we can calculate x only. Am ai right? Please tell me.
Relative speed means a train will be static. Then we can calculate x only. Am ai right? Please tell me.
(1)
Abdul said:
5 years ago
You can easily understand by assuming that one train is a brigde and its length is same as the train, let it be x and the speed of train is 10km/h (46-36).
Now, the time taken to cross the bridge is 36sec.
Dis = speed * time.
= (10*5/18) * 36.
= 100. Is that clear?
We know that 100 is the length of train+length of bridge.
We know both are same so 100÷2 = 50.
Train length is 50 and bridge(another train) length is 50.
Now, the time taken to cross the bridge is 36sec.
Dis = speed * time.
= (10*5/18) * 36.
= 100. Is that clear?
We know that 100 is the length of train+length of bridge.
We know both are same so 100÷2 = 50.
Train length is 50 and bridge(another train) length is 50.
(3)
Shantanu singh parihar said:
5 years ago
We have 2x cause,
When the faster train passes to slower,
It is covering;
X+X distance(slower train +higher speed train),
So the total distance covered is 2X.
When the faster train passes to slower,
It is covering;
X+X distance(slower train +higher speed train),
So the total distance covered is 2X.
(1)
Bhavithra said:
4 years ago
What is the meaning of relative speed?
Shaik Chereesh said:
4 years ago
Relative displacement is x not 2x.
The relative speed is 10.
Time is independent of the frame of reference.
The above points are correct according to my basic knowledge of physics.
Please correct me if the wrong.
The relative speed is 10.
Time is independent of the frame of reference.
The above points are correct according to my basic knowledge of physics.
Please correct me if the wrong.
Basavaraj said:
4 years ago
Answer is 100mtr.
As per the relative speed concept and as per the given question both trains of equal length are at the same point so a faster train has crossed its own length or the length of another one to cross it completely.
So it has to travel x mtr to cross another one with a speed of 10km/hour more.
As per the relative speed concept and as per the given question both trains of equal length are at the same point so a faster train has crossed its own length or the length of another one to cross it completely.
So it has to travel x mtr to cross another one with a speed of 10km/hour more.
(6)
Judah said:
4 years ago
The train should be 100mtr. The solution converts both speeds of the 2 trains to m/s and multiply each m/s by 36 and get the difference of the speed at 36 sec, and that the answer.
Hope it will helps.
Hope it will helps.
(3)
Yuva kumar said:
3 years ago
How 2x/36 = 25/9? Please explain me.
(1)
Shri.. said:
3 years ago
@Bushra Ahmed.
2x=25/9*36 = 900/9 = 100.
2x=25/9*36 = 900/9 = 100.
(2)
Abhishek said:
3 years ago
Why you have done, 2x/36 = 25/9?
And why not 2x/46 = 25/9?
Please explain me clearly.
And why not 2x/46 = 25/9?
Please explain me clearly.
(8)
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