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:
250 comments Page 16 of 25.
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.
Deep said:
1 decade ago
Easy method is by using time and distance formula.
Bala said:
1 decade ago
45*5/18 = 12.5.
12.5*30 = 375.
375-130 = 245.
12.5*30 = 375.
375-130 = 245.
Madan said:
1 decade ago
45*5/18 = 12.5.
12.5*30 = 375.
375-130 = 245.
12.5*30 = 375.
375-130 = 245.
Anusha said:
1 decade ago
Hi friends I did in a different way:
Let the length of train b = 130.
Let the length of bridge b = x.
Therefore distance = x + 130.
Time = 30 sec.
S = 45 km/h = 45*5/18 = 25/2 m/s.
So, in this case distance = 375 m.
So, d = x + 130 substituting the value of d (distance).
We get 375 - 130 = x.
X = 245 m.
Let the length of train b = 130.
Let the length of bridge b = x.
Therefore distance = x + 130.
Time = 30 sec.
S = 45 km/h = 45*5/18 = 25/2 m/s.
So, in this case distance = 375 m.
So, d = x + 130 substituting the value of d (distance).
We get 375 - 130 = x.
X = 245 m.
Shashi said:
1 decade ago
We can solve by using formula also @Anusha.
Pradnya said:
1 decade ago
I can't understand your answer please explain.
Jitendra said:
1 decade ago
Can we try this way?
Length of train + Length of bridge = (Distance which train need to be cover in 30 sec).
(130 m + X)---(1)-X = Suppose length of bridge.
Speed of trains = 45 km/h speed given in km/h hence convert it in m/sec.
45*5/18 = 25/2 ----- (2).
From equation (1) and (2).
= 25/2 = (130+X)/30.
= 25*30 = 260+2X.
= 750-260 = 2X.
= 490/2 = X.
= 245 = X.
Hence length of bridge (X) will be 245 m.
Length of train + Length of bridge = (Distance which train need to be cover in 30 sec).
(130 m + X)---(1)-X = Suppose length of bridge.
Speed of trains = 45 km/h speed given in km/h hence convert it in m/sec.
45*5/18 = 25/2 ----- (2).
From equation (1) and (2).
= 25/2 = (130+X)/30.
= 25*30 = 260+2X.
= 750-260 = 2X.
= 490/2 = X.
= 245 = X.
Hence length of bridge (X) will be 245 m.
Dinesh said:
1 decade ago
As the train crosses, which means the train should start at the starting of bridge and completely leave the bridge.
So, (130+x+130) should be the distance traveled in 30 secs.
= (130+x+130)/30 = (45*5/18).
x = 115.
So, (130+x+130) should be the distance traveled in 30 secs.
= (130+x+130)/30 = (45*5/18).
x = 115.
Poonam Pipaliya said:
1 decade ago
What is role of 30 sec and from where it comes?
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