A 110 m long train is running at a speed of 60 km/h. How many seconds, does it take to cross an another train of length 170 m, which is standing on parallel track?

Options

A. 15.6s
B. 16.8s
C. 17.2s
D. 18s

Answer

To solve the problem of how long it takes for a moving train to cross a stationary train on a parallel track, we can follow these steps:

### Step 1: Understand the Problem
We have a moving train (Train 1) that is 110 meters long and is traveling at a speed of 60 km/h. There is another train (Train 2) that is 170 meters long and is stationary.

### Step 2: Convert Speed from km/h to m/s
To work with consistent units, we need to convert the speed of Train 1 from kilometers per hour to meters per second. The conversion factor is:
\[ 1 \text{ km/h} = \frac{5}{18} \text{ m/s} \]
Thus, the speed of Train 1 in m/s is:
\[ 60 \text{ km/h} \times \frac{5}{18} = \frac{300}{18} = 16.67 \text{ m/s} \]

### Step 3: Calculate the Total Distance to be Covered
To cross Train 2, Train 1 must cover a distance equal to the sum of its own length and the length of Train 2. Therefore, the total distance \(D\) is:
\[ D = \text{Length of Train 1} + \text{Length of Train 2} = 110 \text{ m} + 170 \text{ m} = 280 \text{ m} \]

### Step 4: Calculate the Time Taken to Cross
The time \(t\) taken to cross can be calculated using the formula:
\[ t = \frac{D}{\text{Speed}} \]
Substituting the values we have:
\[ t = \frac{280 \text{ m}}{16.67 \text{ m/s}} \approx 16.8 \text{ seconds} \]

### Final Answer
The time taken for Train 1 to cross Train 2 is approximately **16.8 seconds**.

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