Problem on Trains
- A passenger train running at a speed of 72 km/hr crosses a 400m long platform in 30 sec. What is the length of the train?
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Speed in m/sec = Speed in Km/hr x 5/18
Distance covered by train in crossing the platform = Length of train + Length of PlatformCorrect Option: A
Speed of train in m/sec = 72 km/hr x 5/18 = 20 m/sec
Distance covered in meter = Time taken in crossing the platform in sec x speed in meter = 30 sec x 20 m/sec = 600m
Now, we know , Distance covered by train in crossing the platform = Length of train + Length of Platform
Therefore, length of the train = 600m - 400m = 200m
- The length of train is equal to the length of the platform. Suppose the train is running at a speed of 36 km/hr and it crosses a platform in 2 minutes. What is then the length of the train?
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Distance covered by train in crossing the platform = Length of train + Length of Platform
Correct Option: D
Speed in m/sec = 36km/hr x (5/18) = 10 m/sec
Given, Time taken by train to cross the platform = 2 min = 120 sec
Therefore, the distance covered by train in crossing the platform = 10 m/sec x 120 sec = 1200 m
Now, distance covered by train in crossing the platform = Length of train + Length of Platform
Given, Length of train = Length of Platform = x
Therefore, 2x = 1200
so, x = Length of train = 1200/2 = 600 m
- A train takes 24 sec to cross a 480 m platform and 36 sec to cover a 900 m platform. what is the length of the train?
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Speed of train will remain constant for both of the situation
Correct Option: A
Let the length of the train be x meter and its speed be y m/sec
Then, (x + 480 m) / 24 sec = y ....(i)
and , (x + 720 m) / 36 sec = y ....(ii)
From Eqs (i) and (ii)
(x + 480) / 24 = (x + 900) / 36
⇒ 3x + 1440 = 2x + 1800
∴ Length of train, x= 360m
- A train runs with a speed of 200 km/hour. What will be its speed in m/sec?
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Speed in m/sec = (Speed in Km/ hour) x 5/18
Correct Option: B
Speed in km/ hour =200
Speed in m/sec = 200 x 5/18 = 500/9 m/sec = 55.55 m/sec
- A train 400 m long is running at a speed of 54 km/hr. If it crosses a tunnel in 2 minutes. Then what is the length of tunnel?
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Distance covered in crossing the tunnel = Length of train + Length of tunnel
Speed in m/sec = (speed in km/hr) x 5/18Correct Option: B
Speed of train in m/sec = (speed of train in km/hr) x 5/18
∴ speed of train in m/sec = 54 x 5/18 = 15 m/sec
Time taken to cross the tunnel = 2 minutes = 120 sec
Therefore, Total length covered by train in crossing the tunnel = Speed of train x Time taken to cross the tunnel
= 15 m/sec x 120 sec = 1800 m
Now, we know that
Total length covered by train in crossing the tunnel = Length of train + Length of tunnel
Given, Length of train =400m and
Calculated above, Length covered by train in crossing the tunnel = 1800 m
Therefore, Length of tunnel = 1800m- 400m = 1400m
