Solving Relative Speed Problems
This problem involves calculating the time it takes for two people moving in the same direction to be a certain distance apart, based on their different speeds.
Determining Relative Speed
When two objects move in the same direction, their relative speed is the difference between their individual speeds. This represents how quickly the distance between them changes.
- Sohan's speed:
- Mohan's speed:
Since Mohan is faster, the relative speed at which they move apart is:
Relative Speed = SpeedMohan - SpeedSohan
Relative Speed = $4 \text{ km/hr} - 3.5 \text{ km/hr} = 0.5 \text{ km/hr}$
Calculating Time to Reach Distance Apart
The relationship between distance, speed, and time is given by the formula:
Distance = Speed $\times$ Time
In this case, the 'Distance' is the separation distance (1.5 km), and the 'Speed' is the relative speed (0.5 km/hr).
We need to find the 'Time'. Rearranging the formula:
Time = $\frac{\text{Distance}}{\text{Relative Speed}}$
Plugging in the values:
Time = $\frac{1.5 \text{ km}}{0.5 \text{ km/hr}}$
Time = $3 \text{ hours}$
Conclusion
They will take 3 hours to be 1.5 km apart.
Similar Questions
- 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:
- 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:
- 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?
- 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?
- 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?
- 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?
- 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?
- 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 persons A and B are travelling towards each other at the speeds of 10 km/h and 14 km/h. The distance between them is 24 km. Find the time taken by them to meet each other.
Important Questions from Relative Speed
The driver of a car, which is travelling at a speed of 75 km/h, locates a bus 80 m ahead of him, travelling in the same direction. After 15 seconds, he finds that the bus is 40 m behind the car. What is the speed of the bus (in km/h)?
The distance between two station A and B is 800 km. A train X starts from A and moves towards B at 40 km/h and another trains Y starts from B and moves towards A at 60 km/h. how far from A will they cross each other?
A and B are travelling towards each other from the points P and Q respectively. After crossing each other, A and B take \(6\frac{1}{8}\) hours and 8 hours, respectively, to reach their destinations Q and P, respectively. If the speed of B is 16.8 km/h, then the speed (in km/hr) of A is:
A train leaves station A at 8 am and reaches station B at 12 noon. A car leaves station B at 8:30 am and reaches station A at the same time when the train reaches station B. At what time do they meet?
A and B start moving towards each other from places X and Y respectively, at the same time. The speed of A is 20% more than that of B. After meeting on the way, A and B take \(2\frac{1}{2}\) hours and x hours now to reach Y and X respectively. What is the value of x?
