Two trains P and Q, measure 200 m and 300 m in length, respectively. The faster train, coming from behind, takes 48 seconds to overtake the slower when moving in the same direction. When they approach each other from opposite directions, they cross each other completely in 20 seconds. Determine the speed of the faster train.
63.75 km/h
Combined length of both trains: \(200+300=500\) m \(=0.5\) km.
Same direction (overtaking): relative speed \(=(u-v)\), and \((u-v)\times\tfrac{48}{3600}=0.5 \Rightarrow u-v=37.5\) km/h.
Opposite directions (crossing): relative speed \(=(u+v)\), and \((u+v)\times\tfrac{20}{3600}=0.5 \Rightarrow u+v=90\) km/h.
Adding the two equations: \(2u=127.5 \Rightarrow u=63.75\) km/h.
Hence, the speed of the faster train is 63.75 km/h.
Similar Questions
- Sohan and Mohan start from the school with a speed of 3.5 km/hr and 4 km/hr. What time will they take to be 1.5 km apart if they start in the same direction?
- A started a journey at 1:00 p.m. at a speed of 40 km/h. B started from the same spot and in the same direction at 1:40 p.m. at a speed of 50 km/h. How many minutes will B take to catch up with A?
- P can run 250 m in 25 s and Q can run the same distance in 30 s. By what distance is P ahead of Q after 4.5 s, if both start the race at the same time?
- Ravi and Mohan start moving together from a point in opposite directions on bikes. Ravi's speed is 80 km/h and Mohan's speed is 40 km/h. What will be the distance between them after 15 min?
- A dog saw a cat at a distance of 280 m. The cat at once ran with the speed of 10 km/h and the dog also ran to catch it with the speed of 24 km/h. How much time will the dog take to catch the cat?
- Two trains of length 200 m and 400 m run on parallel lines. When they run in the same direction, it takes 30 seconds for the train with the higher speed to overtake the other train, and when they travel in the opposite directions, it takes them 6 seconds to cross each other. What are the speeds (in km/h) of the two trains?
- Raju is standing away from Karthik at a distance of 300 m. Raju starts running and Karthik chases him. Raju and Karthik run at the rate of 10 km and 12 km per hour respectively. What is the distance between them after 6 minutes?
- Two trains are running in the same direction with the speeds of $32\text{ km/h}$ and $26\text{ km/h}$ respectively from X and Y. If X is $42\text{ km}$ away from Y and if they meet at a point Z beyond Y, then the distance from Y to Z will be:
- A bus moving at the speed of 45 km/h overtakes a truck 150 m ahead, going in the same direction in 30 sec. The speed of the truck is:
- A carriage driving in a fog passed a man who was walking at the speed of 3 km/h in the same direction. He could see the carriage for 4 min and it was visible to him up to a distance of 100 m. What was the speed of the carriage?
Important Questions from Relative Speed
In a circular race of 2500 m, a man and a woman start from a point towards opposite directions with speeds of 37 km/h and 35 km/h, respectively. After how much time from the start of the race will they meet for the first time?
- X and Yrun a 3 km race along a circular course of length 300 m. Their speeds are in the ratio 3 : 2. If they start together in the same direction, how many times would the first one pass the other (the start-off is not counted as passing)?
A train of length 600 meters passes another train of length 1000 meters moving in the opposite direction in 96 seconds. If the speed of both the trains is the same, then what is the speed of each train?
The distance between Delhi and Patna is $480$ km. A train starts from Delhi and travels towards Patna at a speed of $60$ kmph. Another train starts from Patna towards Delhi at a speed of $80$ kmph, but starts $1$ hour after the first train. In how much time, after the first train started, will they meet each other?
Ram traveling at the speed of 3 km/h reaches 15 minutes late. Had he walked at 4 km/h, he would have reached 15 minutes earlier. How much distance does Ram have to cover?
