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:
234 comments Page 20 of 24.
Krupa said:
1 decade ago
The 2x is bcoz
Let the length of the train a =x
Length of the train b =y since both the trains are equal in length uwe can take
Length of train b as also "x"
So, Distance=x+x=2x
simple :-)
Let the length of the train a =x
Length of the train b =y since both the trains are equal in length uwe can take
Length of train b as also "x"
So, Distance=x+x=2x
simple :-)
Ram Chaudhary said:
1 decade ago
Here the length of first train is x meters
and the distance covered by the two train is 2x meters
{Here we have to convert km/hr into m/sec because the answer is in the meter}
Relative speed between them is ((46-36)*))5/18 then we get
25/9 m/sec
after that we must equating the two equations then we get the length of the first train
we are using the formula distance=time*speed
distance=2x
time=36 sec
speed=25/9
2x=25/9*36
we get x=50 m
and the distance covered by the two train is 2x meters
{Here we have to convert km/hr into m/sec because the answer is in the meter}
Relative speed between them is ((46-36)*))5/18 then we get
25/9 m/sec
after that we must equating the two equations then we get the length of the first train
we are using the formula distance=time*speed
distance=2x
time=36 sec
speed=25/9
2x=25/9*36
we get x=50 m
Rajkumar said:
1 decade ago
Equal length, L1=L2
speed s1,s2
in same direction formula, time=(L1+L2)/(s1-s2) m/sec.
s1=46 km/hr
s2=36 km/hr
time=36 sec
time=(L1+L2)/(46-36)*5/18
36=(L1+L1)/(10)*5/18 [:.Equal length, L1=L2]
36=2L/(50/18)
36=(2L*18)/50
2L=(36*50)/18
2L=100
L=50 m
Using this formula.
speed s1,s2
in same direction formula, time=(L1+L2)/(s1-s2) m/sec.
s1=46 km/hr
s2=36 km/hr
time=36 sec
time=(L1+L2)/(46-36)*5/18
36=(L1+L1)/(10)*5/18 [:.Equal length, L1=L2]
36=2L/(50/18)
36=(2L*18)/50
2L=(36*50)/18
2L=100
L=50 m
Using this formula.
Arup said:
1 decade ago
Why we have to subtract (46-36)kmph?
though it is relative speed and both of them are coming to each other it should get added i.e (46+36)
though it is relative speed and both of them are coming to each other it should get added i.e (46+36)
Hasi said:
1 decade ago
Distance traveled by train =x
2 trains have same length
there are two trains traveled at the same time
means total distance traveled by the train =2x
Relative distance of the train is =(46-36)=10km/hr
but options are given in sec so,we have to convert into m/sec
10*(5/18)=25/9
total distance=speed*time
2x=(25/9)*36
2x=100
x=50
2 trains have same length
there are two trains traveled at the same time
means total distance traveled by the train =2x
Relative distance of the train is =(46-36)=10km/hr
but options are given in sec so,we have to convert into m/sec
10*(5/18)=25/9
total distance=speed*time
2x=(25/9)*36
2x=100
x=50
Vinayak said:
1 decade ago
Can we calculate this example by (a+b) / (u-v)?
Ster said:
2 decades ago
2x as distance only makes sense if the faster train start behind the slower train. If they were right next to each other at the start, the distance traveled would only be x. Question does not clarify this. Please amend.
Venkatesh said:
2 decades ago
Hi jelli, can you give a important equations used in that kind of problems.
Venkatesh said:
2 decades ago
Thanks jelli.
Sid said:
2 decades ago
What is relative speed. Please explain me in somewhat detail manner. Cant understand.
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