Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 3)
3.
The length of the bridge, which a train 130 metres long and travelling at 45 km/hr can cross in 30 seconds, is:
Answer: Option
Explanation:
| Speed = |  |
45 x | 5 |  m/sec |
= | |
25 | m/sec. |
| 18 | 2 |
Time = 30 sec.
Let the length of bridge be x metres.
| Then, | 130 + x | = | 25 |
| 30 | 2 |
2(130 + x) = 750
x = 245 m.
Video Explanation: https://youtu.be/M_d8WufJWKc
Discussion:
245 comments Page 4 of 25.
Mano said:
1 decade ago
Your are right sushi.
Please help why we consider both lengths separately?
If the train is crossed 130m length in 10 sec it also covered length of bridge?
Why we are again consider the bridge length?
The train is already crossed the bridge in 10 sec. So the length of the bridge also covered.
Please help why we consider both lengths separately?
If the train is crossed 130m length in 10 sec it also covered length of bridge?
Why we are again consider the bridge length?
The train is already crossed the bridge in 10 sec. So the length of the bridge also covered.
Varalakshmi saravanan said:
1 decade ago
Hi Friends it's very simple.
Length of the Train = 130 m.
Speed = 45 km/hr after converting into m/s we will get (45*5/18) => 25/2.
Time = 30 sec.
Length of bridge = x + length of train.
X+length of train = Speed of the train*time.
X+130 = 25/2*30.
X+130 = 375.
X = 375-130.
X = 245.
Length of the Train = 130 m.
Speed = 45 km/hr after converting into m/s we will get (45*5/18) => 25/2.
Time = 30 sec.
Length of bridge = x + length of train.
X+length of train = Speed of the train*time.
X+130 = 25/2*30.
X+130 = 375.
X = 375-130.
X = 245.
Pranil T. Mhatre said:
1 decade ago
Speed of the Train = 45 km/hr.
Speed of the train in meters/sec = (45*1000)/(60*60) = (25/2).
Distance covered by train in 30 secs = (25/2)*30 = 375 meters.
Now the train having the length 130 meters had crossed the bridge in 30 secs so the length of the Bridge = 375 - 130 = 245 meters.
Speed of the train in meters/sec = (45*1000)/(60*60) = (25/2).
Distance covered by train in 30 secs = (25/2)*30 = 375 meters.
Now the train having the length 130 meters had crossed the bridge in 30 secs so the length of the Bridge = 375 - 130 = 245 meters.
Manmohan said:
10 years ago
For a quick solution:
Let the length of the bridge be x.
Speed = 45*5/18 = 75/6 m/sec.
Time = 30 sec.
Length of train 130 m.
So we know Speed = Total distance/Time.
=> Total distance = Speed*Time.
=> x+130 = 75/6*30.
=> x= 245.
Hence the length of the bridge is 245 m.
Let the length of the bridge be x.
Speed = 45*5/18 = 75/6 m/sec.
Time = 30 sec.
Length of train 130 m.
So we know Speed = Total distance/Time.
=> Total distance = Speed*Time.
=> x+130 = 75/6*30.
=> x= 245.
Hence the length of the bridge is 245 m.
Kalimuthu said:
1 decade ago
A train cross 1 hour =45km
so that Trian cross in 1 hour =45000m(1km=1000m)
so that trian cross in3600seconds=45000m(1hour=3600sec)
so that trian cross in one second is 45000/3600=12.5m
now 30 sec cross the bridge 12.5*30=375
so that trian length is 130m
so we proof 375-130=245METERS
so that Trian cross in 1 hour =45000m(1km=1000m)
so that trian cross in3600seconds=45000m(1hour=3600sec)
so that trian cross in one second is 45000/3600=12.5m
now 30 sec cross the bridge 12.5*30=375
so that trian length is 130m
so we proof 375-130=245METERS
Vikram said:
1 decade ago
Here, A Train 130meter long.
Speed of train=45km/hr=45000m/3600sec=12.5m/sec.
Within 30sec that train cross distance=12.5m/sec*30sec=375m/30sec.
So,Length of Bridge=Cross distance - length of Train
=375-130=245Meters.
Therefore , The Length of Train= 245Meters.
Speed of train=45km/hr=45000m/3600sec=12.5m/sec.
Within 30sec that train cross distance=12.5m/sec*30sec=375m/30sec.
So,Length of Bridge=Cross distance - length of Train
=375-130=245Meters.
Therefore , The Length of Train= 245Meters.
Kaviprema said:
2 years ago
Soln,
L.t -130m ,s -45km/hr ,t -30 sec
L.b - ?.
Let us assume length of the bridge as x,
D = s* t.
130 (l.t) + x(l.b) = 45 km/hr * 30 sec.
130 + x =45 * 5/18 m/ sec * 30 sec.
After solving we will get,
130 + x = 375,
x = 375 -130,
x = 245 m.
So, the length of the bridge is 245 m.
L.t -130m ,s -45km/hr ,t -30 sec
L.b - ?.
Let us assume length of the bridge as x,
D = s* t.
130 (l.t) + x(l.b) = 45 km/hr * 30 sec.
130 + x =45 * 5/18 m/ sec * 30 sec.
After solving we will get,
130 + x = 375,
x = 375 -130,
x = 245 m.
So, the length of the bridge is 245 m.
(28)
Dileep kumar said:
1 decade ago
Hai friends don't be confuse with considering different formulas, let use single formula to solve these all type of questions, i.e.
Distance = speed*time; OR (D = ST) ;
Let us consider bridge length = x;
Total length (x+130) = (25/2) *30;
x + 130 = 375;
x = 375-130;
x = 245.
Distance = speed*time; OR (D = ST) ;
Let us consider bridge length = x;
Total length (x+130) = (25/2) *30;
x + 130 = 375;
x = 375-130;
x = 245.
Deepak said:
1 decade ago
Simple Answer to solve this problem :
Step 1> Speed of the train with respective to bridge is 45 km/hr in terms of m/s is 45*(5/18)=12.5(v-velocity) .
Step 2> let x be the length of the bridge so v=d/t where d=x+130 answer 12.5=(x+130)/30 (t-time).
245(meters) = x.
Step 1> Speed of the train with respective to bridge is 45 km/hr in terms of m/s is 45*(5/18)=12.5(v-velocity) .
Step 2> let x be the length of the bridge so v=d/t where d=x+130 answer 12.5=(x+130)/30 (t-time).
245(meters) = x.
Yuvashree R said:
1 year ago
Convert speed from km/hr to m/sec(km/hr=5/18 m/s).
Then,as we know DISTANCE=SPEED *TIME.
D = [45 * (5/18)] * 30 sec.
Then, D = 375m(This is the total distance)
So, we can subtract the total distance from the length of the train),
The length of the train is = 375 - 130 = 245m.
Then,as we know DISTANCE=SPEED *TIME.
D = [45 * (5/18)] * 30 sec.
Then, D = 375m(This is the total distance)
So, we can subtract the total distance from the length of the train),
The length of the train is = 375 - 130 = 245m.
(84)
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