# Time to Cross Trains: 200m & 150m, 40km/hr & 45km/hr

• neha1
Can you give some equations and explain your thinking?In summary, two trains, one 200 meters and the other 150 meters, are traveling on parallel rails at speeds of 40 km/hr and 45 km/hr. The question asks for the time it takes for the trains to cross each other if they are traveling in the same direction. This can be solved using the equation time = distance/speed. By finding the total distance traveled by the trains and dividing it by the combined speed, we can determine the time it takes for them to cross each other.
neha1
two trains 200 meters and 150 metrers are running on the parallel raila at this rate of 40km/hr and 45 km/hr.in how time will they cross each other if they are running in the same direction?

neha1 said:
two trains 200 meters and 150 metrers are running on the parallel raila at this rate of 40km/hr and 45 km/hr.in how time will they cross each other if they are running in the same direction?
Hi neha1 and welcome to PF,

For future reference, we have https://www.physicsforums.com/forumdisplay.php?f=152" for such questions, but don't worry your thread will get moved there later.

Now for your question. What have you attempted thus far?

Last edited by a moderator:

Based on the given information, we can calculate the relative speed of the two trains by subtracting the slower train's speed from the faster train's speed. In this case, the relative speed would be 45km/hr - 40km/hr = 5km/hr. This means that the two trains are getting closer to each other at a rate of 5 kilometers per hour.

To determine the time it would take for the trains to cross each other, we can use the formula Time = Distance/Speed. In this case, the distance between the two trains would be the sum of their lengths, which is 200m + 150m = 350m. Converting this distance to kilometers, we get 0.35km.

So, the time it would take for the trains to cross each other would be 0.35km/5km/hr = 0.07 hours. Converting this to minutes, we get 0.07 hours x 60 minutes/hour = 4.2 minutes. Therefore, it would take approximately 4.2 minutes for the two trains to cross each other if they are running in the same direction.

## 1. How do you calculate the time it takes for a train to cross a distance at a given speed?

The time it takes for a train to cross a distance can be calculated using the formula: time = distance / speed. In this case, the distance is given as 200m and 150m, and the speeds are 40km/hr and 45km/hr respectively. So, the time for the first train to cross 200m would be 200m / 40km/hr = 5 seconds, and the time for the second train to cross 150m would be 150m / 45km/hr = 3.33 seconds.

## 2. How do you convert km/hr to m/s?

To convert kilometers per hour (km/hr) to meters per second (m/s), we need to divide the speed in km/hr by 3.6. Thus, a speed of 40km/hr would be equivalent to 40 / 3.6 = 11.11 m/s, and a speed of 45km/hr would be equivalent to 45 / 3.6 = 12.5 m/s.

## 3. Why is the time for the train to cross 150m shorter than the time for the train to cross 200m?

The time taken for a train to cross a distance is inversely proportional to its speed. This means that the higher the speed, the shorter the time taken to cover the same distance. In this case, the second train has a higher speed of 45km/hr compared to the first train's speed of 40km/hr. Therefore, it takes less time for the second train to cover a shorter distance of 150m compared to the first train's time to cover 200m.

## 4. Is it possible for the two trains to cross at the same time?

No, it is not possible for the two trains to cross at the same time. This is because they have different speeds and are covering different distances. The train with a higher speed will always take less time to cross a given distance compared to the train with a lower speed.

## 5. How does the length of the train affect the time taken to cross a distance?

The length of the train does not affect the time taken to cross a distance. The time taken is solely dependent on the speed of the train and the distance it needs to cover. The length of the train only affects the distance it needs to cover, but not the time it takes to cross that distance.

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