## Friday, November 27, 2015

### Time Speed Distance - Average Speed, Relative Speed, Boats and Streams Video Tutorial

In this video I have started the much awaited topic of Time Speed and Distance. In this video I have first told you the concepts of average speed which is equal to total distance travelled divided by total time taken. Then I have solved some questions to give an idea about what type of questions you see relating to this concept of average speed and how to solve them. Then I have shown what type of questions can be asked which are directly related to the easiest formula of Time Speed and Distance which is Distance is equal to Speed multiplied by Time. I have solved questions related to this. Then finally I have explained the very important concept of relative speed. The concept of relative speed is used both in time speed distance and also in the questions of boats and streams. There is a very slight difference between the usage of both of them. That difference has been properly explained through question solving in this video. The questions that I have solved in this video are listed below.
Question 1. Ram goes from Delhi to Jaipur at a speed of 40 km per hour and comes back at a speed of 60 km per hour taking exactly the same path. Find his average speed of the entire journey ?

Question 2. Shyam travelled first 1/3rd of the distance of his journey at a speed of 40 km per hour, 1/3rd of his remaining distance at 50 km per hour and the rest at 90 km per hour. Find his average speed ?

Question 3. A car travels at 50 km per hour for the first half time of the journey, at 25 km per hour for the half of the remaining time of the journey, at 12.5 km per hour for the half of the remaining time of the journey and so on until the car accomplishes its journey. The average speed of the car is approximately equal to

Question 4. Excluding stoppages, the average speed of a bus is 54 km per hour, and including stoppages it is 45 km per hour. For how many minutes does the bus stop per hour ?

Question 5. If Rohan walks from his house to his school at the rate of 4 km per hour, he reaches school 10 minutes earlier than the scheduled time. However, if he walks at the rate of 3 km per hour, he reaches school 10 minutes later than the scheduled time. Find the distance between the school and Rohan's house ?

Question 6. Rajlaxmi takes 20 minutes less than the usual time to reach her office if her speed increases by 5 km per hour, and takes 30 minutes more than the usual time if her speed decreases by 5 km per hour. What is her usual speed ?

Question 7. Two trains start at the same time from Shimla and Jammu and proceed towards each other at 80 km per hour and 95 km per hour respectively. When they meet, it is found that one has travelled 180 km more than the other. Find the distance between Shimla and Jammu ?

Question 8. Ruchi and Shailly start simultaneously from A and B towards B and A respectively. They meet on the way at C which is at a distance of 120 meters from A. If Ruchi and Shailly takes 16 seconds and 25 seconds to reach their respective destinations from C, then what is the distance between A and B ?

Question 9. Mohan and Arun start swimming simultaneously from the opposite ends of a pool which is 50 meters long. They pass each other, reach the respective ends and immediately turn back. Now they meet at a distance of 15 meters from where Mohan started, 10 seconds after the start. Find the speed of Arun ?

Question 10. M and N were 580 miles apart and they started driving towards each other. M's car had travelled at the speed of 20 miles per hour, 4 hours a day for 5 days, when it had met N's car. If N had driven for 3 hours a day for 5 days, what was the speed of N's car ?

Question 11. Two boats start simultaneously towards each other at different speeds from the parallel and opposite banks of a lake. When they pass each other for the first time, they are 300 meters from one of the banks. After the first meeting, they continue to move towards the opposite banks. Once they reach the opposite banks, they turn around and move towards each other once again. When they pass each other for the second time, they are 200 meters from the other bank. Find the ratio of the speeds of the two boats ?

1. Are this videos free of cost?

2. you have said that this website is against commercialization of education. you are charging rent for each video . you are no differrent . just money minded

3. 4. Sir, Is any aptitude video of your lecture available in dvds for sale? if any. please tell me i would like to buy it.

5. sir,
how to solve this question
Nagraj and Monohar are travelling to city B on the same road.Nagraj overtakes Manohar at place A at 9am .Nagraj reach B at 5pm He stays at B for two hours and then returns.While returning to A,Nagaraj crosses Manohar at a place called E at 9:00pm.Assuming that they travel at uniform speeds and travel without stops in between find out at what time will Manohar reaches B.
1.4:00am 2.3:00am 3.12:30am 4.1:00am

1. Lets assume distance between A and B is 64 Km.
Nagraj covers distance from A to B in 8 Hours. So his speed is 64/8 = 8 Km/Hour
He returns from B to E in 2 hours so he will cover distance 2 X 8 = 16 Km.
So distance from A to E is 64-16 = 48 Km and E to B is 16 Km.
Meantime Manohar has covered 48 kms in 12 hours. So his speed is 4 Km/s

So remaining distance 16 Km will be covered by Manohar in 16/4 = 4 Hours

So he will reach at B at 9 PM + 4 hours i.e. at 1 AM.

Thanks to Sir.

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