Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 14)
14.
Two trains 140 m and 160 m long run at the speed of 60 km/hr and 40 km/hr respectively in opposite directions on parallel tracks. The time (in seconds) which they take to cross each other, is:
Answer: Option
Explanation:
| Relative speed = (60 + 40) km/hr = |  |
100 x | 5 |  m/sec |
= | |
250 | m/sec. |
| 18 | 9 |
Distance covered in crossing each other = (140 + 160) m = 300 m.
| Required time = | |
300 x | 9 | sec |
= | 54 | sec = 10.8 sec. |
| 250 | 5 |
Discussion:
42 comments Page 3 of 5.
Praveen said:
10 years ago
Let time is x sec. According to question:
Speed = Length/Time.
Both are in opposite so we add the speed if in same direction then sub speed.
So speed = 60+40 = 100 km/h.
We convert it in m/s by multiply 5/18.
So speed = 250/9 m/s.
Length = 140 m + 160 m = 300 m.
And time = x sec.
So 250/9 = 300/x.
So x = (300*9)/250.
And time = 10.8 sec.
Speed = Length/Time.
Both are in opposite so we add the speed if in same direction then sub speed.
So speed = 60+40 = 100 km/h.
We convert it in m/s by multiply 5/18.
So speed = 250/9 m/s.
Length = 140 m + 160 m = 300 m.
And time = x sec.
So 250/9 = 300/x.
So x = (300*9)/250.
And time = 10.8 sec.
Praveen Sharma said:
10 years ago
x = (300*9)/250.
x = 2700/250 {Cut zero by zero}
x = 270/25.
x = 54/5 {Both no. divided by 5}
x = 10.8 sec.
x = 2700/250 {Cut zero by zero}
x = 270/25.
x = 54/5 {Both no. divided by 5}
x = 10.8 sec.
Praveen Sharma said:
10 years ago
Convert km/h in m/sec.
In first we have 1 km = 1000 m.
In second we have 1 hour = 60 min.
And 1 min = 60 sec.
So total sec in 1 hrs = 60 x 60 = 3600 sec.
So 1000 m/3600 sec = 10/36 [cut 2 zero].
And finally divided by 2 both number.
So 5/18 m/s.
I hope it is useful for non-maths students.
In first we have 1 km = 1000 m.
In second we have 1 hour = 60 min.
And 1 min = 60 sec.
So total sec in 1 hrs = 60 x 60 = 3600 sec.
So 1000 m/3600 sec = 10/36 [cut 2 zero].
And finally divided by 2 both number.
So 5/18 m/s.
I hope it is useful for non-maths students.
Aanchal said:
9 years ago
Got it. Thanks @Praveen Sharma.
Sagar shinde said:
9 years ago
140 + 160/60 + 40.
= 300/100,
= 3,
= 3 * 18/5,
= 10.8.
= 300/100,
= 3,
= 3 * 18/5,
= 10.8.
(1)
Siva said:
9 years ago
In the question, it did not mention which train to considered faster or slower, so how to solve it?
(1)
Varma said:
9 years ago
@All.
Thank you friends I got it.
Thank you friends I got it.
Dharmendra said:
9 years ago
Why did you change 250/9 to 9/250 in the last calculation? Pease explain me.
Syam said:
8 years ago
Thank you all for the given explanation.
Haripriya said:
8 years ago
How it will come 10.8? I am not getting the calculation. Please explain it.
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