Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 21)
21.
How many seconds will a 500 metre long train take to cross a man walking with a speed of 3 km/hr in the direction of the moving train if the speed of the train is 63 km/hr?
Answer: Option
Explanation:
| Speed of the train relative to man | = (63 - 3) km/hr | |||||||
| = 60 km/hr | ||||||||
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|
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 Time taken to pass the man |
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| = 30 sec. |
Discussion:
44 comments Page 1 of 5.
Pradnya Desai said:
5 years ago
The train and the man are moving in the same direction and hence for the train to catch up and pass. The man it should first overcome the speed of the man that is 3km/hr and hence that's why we subtract 3 from 63kms/hr which is the speed of the train.
(2)
Veda said:
5 years ago
After converting 60km/h to m/s.
We want to find the time t = l/s.
T=500/50/3.
3 is in the denominator.
Denominator of the denominator goes to the numerator then we get 500*3/50=30.
We want to find the time t = l/s.
T=500/50/3.
3 is in the denominator.
Denominator of the denominator goes to the numerator then we get 500*3/50=30.
(1)
Sonam Lhadon said:
5 years ago
How it 50/3 becomes 3/50?
Anyone, please explain it.
Anyone, please explain it.
Nirmal said:
5 years ago
@Smith.
In this type of problems, you can consider one object (train or man) is steady and give the velocity of that steady object give to another object.
If they are in the same direction than minus and if the direction is opposite than add the velocities.
In this type of problems, you can consider one object (train or man) is steady and give the velocity of that steady object give to another object.
If they are in the same direction than minus and if the direction is opposite than add the velocities.
(1)
Smith said:
5 years ago
@Vicky.
In case 2.
We count the speed of man in the relative distance. Why don't we count the distance that the man travelled in finding the final time?
It should be 500+Dist Traveled by men.
In case 2.
We count the speed of man in the relative distance. Why don't we count the distance that the man travelled in finding the final time?
It should be 500+Dist Traveled by men.
Vicky said:
6 years ago
Train Speed = 63 km/h = 17.5 m/s.
Man Speed = 3 km/h = 0.83 m/s.
Length of train = 590 m.
If the man and train and moving in the opposite direction then it will take less time to cross each other. If they are moving in the same direction then the train will take more time to cross the man and if the man is stationary then it takes time in between the cases discussed above.
Case 1: Let's suppose man is stationary i.e. Man speed = 0 m/s.
Time = Distance/Speed = 500/17.5 = 28.57 s.
Cast 2: If the man is moving with a speed of 0.83 m/s IN THE DIRECTION OF MOVING TRAIN
Relative speed = 17.5 + 0.833 = 18.33.
Time = Distance/Speed = 500/18.33 = 27.27 s.
Cast 3: If the man is moving with a speed of 0.83 m/s IN THE DIRECTION. " OPPOSITE" TO THE DIRECTION OF MOVING TRAIN.
Relative speed = 17.5 - 0.833 = 16.667.
Time = Distance/Speed = 500/16.667 = 30 s.
Man Speed = 3 km/h = 0.83 m/s.
Length of train = 590 m.
If the man and train and moving in the opposite direction then it will take less time to cross each other. If they are moving in the same direction then the train will take more time to cross the man and if the man is stationary then it takes time in between the cases discussed above.
Case 1: Let's suppose man is stationary i.e. Man speed = 0 m/s.
Time = Distance/Speed = 500/17.5 = 28.57 s.
Cast 2: If the man is moving with a speed of 0.83 m/s IN THE DIRECTION OF MOVING TRAIN
Relative speed = 17.5 + 0.833 = 18.33.
Time = Distance/Speed = 500/18.33 = 27.27 s.
Cast 3: If the man is moving with a speed of 0.83 m/s IN THE DIRECTION. " OPPOSITE" TO THE DIRECTION OF MOVING TRAIN.
Relative speed = 17.5 - 0.833 = 16.667.
Time = Distance/Speed = 500/16.667 = 30 s.
(2)
Sam said:
6 years ago
How come 5/18?
Tell me in details how it came?
Tell me in details how it came?
Muskan said:
6 years ago
I don't know how they calculate the speed of the train.
Kiran said:
6 years ago
It's 500 * 50\3.
= 500*3/50
= 10 * 3.
= 30sec.
= 500*3/50
= 10 * 3.
= 30sec.
Vijay said:
6 years ago
Length of the train = 500m
Speed of the man = 3km/hr
Speed of the train = 63km/hr
Relative speed = 63-3 = 60km/hr = 60 * 5/18 = 50/3(m/s).
Let x be the sec,
500/x = 50/3,
X = 30sec.
Speed of the man = 3km/hr
Speed of the train = 63km/hr
Relative speed = 63-3 = 60km/hr = 60 * 5/18 = 50/3(m/s).
Let x be the sec,
500/x = 50/3,
X = 30sec.
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