Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 8)
8.
A train 360 m long is running at a speed of 45 km/hr. In what time will it pass a bridge 140 m long?
Answer: Option
Explanation:
| Formula for converting from km/hr to m/s: X km/hr = |  |
X x | 5 |  |
m/s. |
| 18 |
| Therefore, Speed = | |
45 x | 5 | m/sec |
= | 25 | m/sec. |
| 18 | 2 |
Total distance to be covered = (360 + 140) m = 500 m.
| Formula for finding Time = | |
Distance | |
| Speed |
 Required time = |
|
500 x 2 | sec |
= 40 sec. |
| 25 |
Discussion:
78 comments Page 7 of 8.
Rohit yadav said:
1 decade ago
If the units are in km/hr .
for example speed= 10km/hr
and time = 5 sec.
Then to find distance in meters..... How will you calculate?
Hence distance= speed x time
= 10 km/hr x 5 sec. (SI units are mismatching)
= 10 x(1000/3600) m/s x 5 s (SI units are matching0
= 10 x (5/18) x 5 m
=125/9 meters answer//
for example speed= 10km/hr
and time = 5 sec.
Then to find distance in meters..... How will you calculate?
Hence distance= speed x time
= 10 km/hr x 5 sec. (SI units are mismatching)
= 10 x(1000/3600) m/s x 5 s (SI units are matching0
= 10 x (5/18) x 5 m
=125/9 meters answer//
Gaurav said:
1 decade ago
Total length = bridge length + train length = 140+360=500.
Let time taken by train be x.
Then,
500/x=45*5/18 m/sec.
500/x=25/2.
1000=25x.
x=40 sec answer.
Let time taken by train be x.
Then,
500/x=45*5/18 m/sec.
500/x=25/2.
1000=25x.
x=40 sec answer.
Swayoni said:
1 decade ago
Why the distance is calculated as (360+140) ? why not only 360?
Paddy said:
2 decades ago
5/18 comes .because we want to express the unit of speed to m/s
1km/hr=1000m/3600s=5/18 m\s
1km/hr=1000m/3600s=5/18 m\s
Venkatesh said:
1 decade ago
I don't get the reason for distance to be covered as 360+140 can any one suggest the reason with pleasure.
Satish said:
1 decade ago
When a train is crossing a bridge means that train is crossing it's own length and the bridge length. If you see at the end of the compartment to be crossed the bridge, the length of the bridge is depending on the train length, if the train is shorter the the time taken to cross the bridge will be lesser and if the train is longer, the time taken to bridge will be larger to cross at the end of the compartment.
Sikkanthar said:
1 decade ago
It is very simple problem.
Here we are going to calculate the value of the time.
All we know the distance or length is nothing but (train length + platform length) from this value we can calculate the time value like.
Length/speed = time.
Convert the speed value m/s into kmph.
Here we are going to calculate the value of the time.
All we know the distance or length is nothing but (train length + platform length) from this value we can calculate the time value like.
Length/speed = time.
Convert the speed value m/s into kmph.
Yash said:
1 decade ago
The Distance travelled by train + bridge length should divide with speed. Simple logic.
Vinod Anand said:
1 decade ago
Total Length of Train and Bridge = 360+140 = 500 Mtr.
And Speed is = 45km/hr.
Than T = 500*18/45*5.
= 200/5.
= 40 sec.
And Speed is = 45km/hr.
Than T = 500*18/45*5.
= 200/5.
= 40 sec.
Shrif said:
1 decade ago
This answer will getting by converting the values of distance and cross multiplication to get this answer easily.
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