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Question

A train 100 m long passes a platform 100 m long in 10 seconds. The speed of the train is

This question was previously asked in
CDS I 2018 Elementary Mathematics Previous Year Paper (04-Feb-2018)
The correct answer is

72 kmph

Determining Train Speed When Passing a Platform

This question asks for the speed of a train given its length, the length of a platform it passes, and the time it takes to complete the passage. We need to calculate the speed in kilometers per hour (kmph).

Key Concepts for Train Problems

When calculating the speed of a train passing a stationary object like a platform, bridge, or tunnel, the total distance covered is the sum of the train's length and the object's length. This is because the train starts passing the object when its front end reaches the beginning of the object, and finishes passing when its rear end leaves the end of the object.

  • Train Length: 100 m
  • Platform Length: 100 m
  • Time Taken: 10 seconds

Calculating Total Distance Covered

To find the speed, we first need the total distance the train travels to completely pass the platform.

The formula is:

\(\text{Total Distance} = \text{Length of Train} + \text{Length of Platform}\)

Substituting the given values:

\(\text{Total Distance} = 100 \, \text{m} + 100 \, \text{m}\)

\(\text{Total Distance} = 200 \, \text{m}\)

Calculating Speed in Meters per Second (m/s)

Speed is defined as distance traveled per unit of time. The basic formula is:

\(\text{Speed} = \frac{\text{Distance}}{\text{Time}}\)

Using the calculated total distance and the given time:

\(\text{Speed} = \frac{200 \, \text{m}}{10 \, \text{s}}\)

\(\text{Speed} = 20 \, \text{m/s}\)

Converting Speed to Kilometers Per Hour (kmph)

The question asks for the speed in kmph. To convert from meters per second (m/s) to kilometers per hour (kmph), we use a standard conversion factor.

The conversion factor is:

\(1 \, \text{m/s} = \frac{18}{5} \, \text{kmph}\)

Now, we apply this factor to the speed we calculated:

\(\text{Speed (kmph)} = 20 \, \text{m/s} \times \frac{18}{5} \, \frac{\text{kmph}}{\text{m/s}}\)

Let's perform the calculation:

\(\text{Speed (kmph)} = \frac{20 \times 18}{5}\)

Simplify the expression:

\(\text{Speed (kmph)} = 4 \times 18\)

\(\text{Speed (kmph)} = 72 \, \text{kmph}\)

Conclusion

The calculated speed of the train is 72 kmph.

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Similar Questions

  1. A train is travelling at 48 km/hr completely crosses another train having half its length and travelling in opposite direction at 42 km/hr in 12 s. It also passes a railway platform in 45 s. What is the length of the platform?

  2. A train of length 110 m is moving at a uniform of 132 km/hr. The time required to cross a bridge of length 165 m is

  3. A 225 m long train is running at a speed of 30 km/hr. How much time does it take to cross a man running at 3 km/hr in the same direction?

  4. A man walking at 5 km/hr noticed that a 225 m long train coming in the opposite direction crossed him in 9 seconds. The speed of the train is

  5. A train moving with a speed of 60 km per hour crosses an electric pole in 30 seconds. What is the length of train in meters?

  6. A passenger train and a goods train are running in the same direction on parallel railway tracks. If the passenger train now takes three times as long to pass the goods train, as when they are running in the opposite directions, then what is the ratio of the speed of the passenger train to that of the goods train?

  7. If a train crosses a km-stone in 12 seconds, how long will it take to cross 91 km stone completely if its speed is 60 km/h?

  8. A train completely crossed two persons X and Y moving in the same direction as the train in \(8\) seconds and \(8.1\) seconds respectively. X is walking at a uniform speed of \(3\ \text{km/hr}\) and Y is walking at a uniform speed of \(4\ \text{km/hr}\). What is the speed of the train?

  9. A train 200 m long passes a platform 100 m long in 10 seconds. What is the speed of the train?

  10. The time taken by a train to cross a man travelling in another train is 10 seconds, when the other train is travelling in the opposite direction. However, it takes 20 seconds, if both the trains are travelling in the same direction. The length of the first train is 200 m and that of the second train is 150 m. What is the speed of the first train ?


Important Questions from Problem on Trains

  1. Eight railway stations A, B, C, D, E, F, G and H are connected either by two-way passages or one-way passages. One-way passages are from C to A, E to G, B to F, D to H, G to C, E to C and H to G. Two-way passages are between A and E, G and B, F and D, and E and D.

    If the route between G and C is closed, which one of the following stations need not be passed through while travelling from H to C?

  2. A daily train is to be introduced between station A and station B starting from each end at 6 AM and the journey is to be completed in 42 hours. What is the number of trains needed in order to maintain the Shuttle Service?

  3. The length of a train and that of a platform are equal. If with a speed of 108 km/hr the train crosses the platform in one minute. Then the length of the train (in metres) is:

  4. A train can cross a pole and a bridge 75 meters long in 10 seconds and 25 seconds respectively. Find the length of the train.

  5. A 275 metre long train crosses a platform of equal length in 33 seconds. What is the speed of the train in kmph?

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