UGC NET
   Top Resources
profile-img
Pooja posted an Question
January 14, 2020 • 15:40 pm 51 points
  • UGC NET
  • General Paper 1

Time and distance topic and tricks plz explain with examples

2 Answer(s) Answer Now
  • 0 Likes
  • 7 Comments
  • 0 Shares
  • comment-profile-img>
    Rishab Soni

    hey pooja. sorry for the late reply because I hadn't seen your question. this is a really nice question and can be solved with two ways. first is trial and error method (recommend if you don't know the actual procedure or being lost). Thr second method is the actual formula. For this you need to understand something which might sound complicated. Now, our ultimate aim is to find the speed of the car, right? so we can begin with taking the speed of car as x, which will provide the speed of train as 1.5x. The distance is given as 120Kms. Now we know that Time is Distance/Speed. They both reach the station at the same time, but the train had to compensate for 30 mins (0.5 hours) halting at stations. So the formula we'll get is 120/x - 120/1.5x = 0.5 . Now when we solve it, we can get the answer as 80 Kmph. If you need better clarification, do let me know and I'll find a better way to explain it to you.

  • comment-profile-img>
    Rishab Soni

    hey pooja. sorry for the late reply because I hadn't seen your question. this is a really nice question and can be solved with two ways. first is trial and error method (recommend if you don't know the actual procedure or being lost). Thr second method is the actual formula. For this you need to understand something which might sound complicated. Now, our ultimate aim is to find the speed of the car, right? so we can begin with taking the speed of car as x, which will provide the speed of train as 1.5x. The distance is given as 120Kms. Now we know that Time is Distance/Speed. They both reach the station at the same time, but the train had to compensate for 30 mins (0.5 hours) halting at stations. So the formula we'll get is 120/x - 120/1.5x = 0.5 . Now when we solve it, we can get the answer as 80 Kmph. If you need better clarification, you can ping me on WhatsApp @8658479730

    eduncle-logo-app

    plz explain in better way

  • comment-profile-img>
    Rishab Soni

    hey pooja. sorry for the late reply because I hadn't seen your question. this is a really nice question and can be solved with two ways. first is trial and error method (recommend if you don't know the actual procedure or being lost). Thr s

  • comment-profile-img>
    Rishab Soni best-answer

    Edit : For example 3, the speed of train A and train B is to be taken as 120 and 100 Kmph. And answer of Ex. 1 is 5, not 50.

  • comment-profile-img>
    Rishab Soni best-answer

    Hello. Time and Distance is one of the most commonly appearing questions in UGC NET and you can expect at least 1 question from this topic. While the question on time and distance are less, it usually have a fair amount of complexity and requires exact knowledge of your concept. So now I'll try to explain the common structures of the question and how you can solve them. First, the basics : Time = Distance / Speed (notice here the unit of time varies according to the unit of speed. you'll always have to convert the distance and speed to same unit. That is Distance to KMs and Speed to KM per hour or minutes. The hour or minute unit of speed will give you unit of time being hours or minutes. Similarly, Distance = Speed X Time (be careful about units here too, always try to convert KMs to Meters and Hours to Minutes or vise versa to allow yourself better and accurate calculation) Speed = Distance / Time (unit will be denoted with both of distance and time like Meters per hour, KMs per hour, Meters per second etc) Now let's see some common questions patterns. 1) Average speed when time is same : Here you'll be given average speed of an moving object (car , train) for a number of times and you'll be required to calculate it's average speed for the journey. The formula here is Total Travelled Distance / Total Time Taken. Ex : A car travels 90 KM at 6Kmph and further 60 Km at 4 Kmph. The time taken for first speed = 90/6 = 15H Time taken for 2nd journey = 60/4 = 15 H Total time taken is 15+15 = 30H Total distance = 60+90 = 150 Average speed = 150/30 = 50Kmph. 2) Average speed when distance is same Quick formula = Avg. S = 2(S1*S2)/S1+S2 For example : Mr. X travels to his office @ 70kmph and suddenly returns home @ 80 Kmph. Now this is a tricky question as we cannot simply average out 70 and 80 and say his average speed was 75 because of the simple fact that he will take more time reaching there and less time returning. Let me try to explain to you with an example . Suppose his office is 560 Kms away (LCM OF 70 & 80 or 70X80) His first journey will take 560/70 = 8 Hours similarly second journey will take 560/80= 7Hours So his total distance now is 560X2 = 1120 Kms (travel and return) and total time is 7 + 8 = 15 H so avg. speed is 1120/15 = 74.66 Kmph. now that you know how it works, you can simply put the quick formula too for same result i.e. Avg. S = 2(S1*S2)/S1+S2 => Avg.S = 2(70X80)/70+80 = 11200/150 = 74.66 KMPH 3) Relative Speed in same direction. Q) The distance between two cities A and B is 560 Km. A train starts from City A at 8 AM and travels towards B. and another train starts from city B at 9 AM and travels towards A. at what time they'll meet? A- Quick formula Time Taken= Relative Speed / Distance (started at same time) Notice here train A starts an hour earlier than B. So by the time B starts, A would have covered 120 Km (speed is 120 kmph) so now the distance remaining is 560-120 = 440 Kms while B starts. Formula for relative speed =Speed of A + Speed of B (Notice here the relative speed is added because they are traveling towards each other. If they were travelling in the same direction, the speed had to be deducted) So relative speed = 120 + 100 = 220Kmph remaining distance = 440 Kms. => Time taken = 440/220 = 2Hs now this 2H must be added to the time when they both started moving towards each other. i.e. 9AM so They'll meet at 9AM + 2H = 11AM (You can use the change in relative speed formula I mention to calculate the time of they are traveling in the same direction) 4) Two person A and B start running from the same point at the 6 A.M. A runs towards North @ 8Kmph , B runs towards south @ 10 Kmph. At what time they'll exactly be 63 Kms apart from each other. Quick formula :Time Taken= Distance / S1+S2 = 63/8+10 = 63/18 = 3.5 = 3Hours and 30 mins. Now this 3:30 hours is to added to the starting time i.e. 6 A.M and we'll get the answer as 9:30 AM Note : If they start at different times, the adjustments from my previous examples can be applied. That is, find out how long the early starter has already travelled and subtract it with total distance to get Remaining Distance , Then calculate the time taken by applying the formula. And then add that time to the later starter. These are the most commonly appearing question patterns in UGC NET and I hope this note and further practice will make you more efficient. Best of Luck.

whatsapp-btn

Do You Want Better RANK in Your Exam?

Start Your Preparations with Eduncle’s FREE Study Material

  • Updated Syllabus, Paper Pattern & Full Exam Details
  • Sample Theory of Most Important Topic
  • Model Test Paper with Detailed Solutions
  • Last 5 Years Question Papers & Answers

Sign Up to Download FREE Study Material Worth Rs. 500/-