TIME AND DISTANCE
#1

[attachment=11664]
TIME AND DISTANCE
IMPORTANT FACTS AND FORMULAE

Distance Distance
1. Speed = Time , Time= Speed , Distance = (Speed * Time)

2. x km / hr = x * 5
18
3. x m/sec = (x * 18/5) km /hr

4. If the ratio of the speeds of A and B is a:b , then the ratio of the times taken by them to cover the same distance is 1: 1 a b
or b:a.
5. Suppose a man covers a certain distance at x km/ hr and an equal distance at y km / hr . Then , the average speed during the whole journey is 2xy km/ hr.
x+y

SOLVED EXAMPLES

Ex. 1. How many minutes does Aditya take to cover a distance of 400 m, if he runs at a speed of 20 km/hr?
Sol. Aditya’s speed = 20 km/hr = {20 * 5} m/sec = 50 m/sec
18 9
Time taken to cover 400 m= { 400 * 9 } sec =72 sec = 1 12 min 1 1 min.
50 60 5

Ex. 2. A cyclist covers a distnce of 750 m in 2 min 30 sec. What is the speed in km/hr of the cyclist?
Sol. Speed = { 750 } m/sec =5 m/sec = { 5 * 18 } km/hr =18km/hr
150 5

Ex. 3. A dog takes 4 leaps for every 5 leaps of a hare but 3 leaps of a dog are equal to 4 leaps of the hare. Compare their speeds.
Sol. Let the distance covered in 1 leap of the dog be x and that covered in 1 leap of the hare by y.
Then , 3x = 4y => x = 4 y => 4x = 16 y.
3 3
 Ratio of speeds of dog and hare = Ratio of distances covered by them in the same time
= 4x : 5y = 16 y : 5y =16 : 5 = 16:15
3 3

Ex. 4.While covering a distance of 24 km, a man noticed that after walking for 1 hour and 40 minutes, the distance covered by him was 5 of the remaining distance. What was his speed in metres per second?
7
Sol. Let the speed be x km/hr.
Then, distance covered in 1 hr. 40 min. i.e., 1 2 hrs = 5x km
3 3
Remaining distance = { 24 – 5x } km.
3
 5x = 5 { 24 - 5x }  5x = 5 { 72-5x }  7x =72 –5x
3 7 3 3 7 3
 12x = 72  x=6
Hence speed = 6 km/hr ={ 6 * 5 } m/sec = 5 m/sec = 1 2
18 3 3

Ex. 5.Peter can cover a certain distance in 1 hr. 24 min. by covering two-third of the distance at 4 kmph and the rest at 5 kmph. Find the total distance.
Sol. Let the total distance be x km . Then,
2 x 1 x
3 + 3 = 7  x + x = 7  7x = 42  x = 6
4 5 5 6 15 5

Ex. 6.A man traveled from the village to the post-office at the rate of 25 kmph and walked back at the rate of 4 kmph. If the whole journey took 5 hours 48 minutes, find the distance of the post-office from the village.
Sol. Average speed = { 2xy } km/hr ={ 2*25*4 } km/hr = 200 km/hr
x+y 25+4 29
Distance traveled in 5 hours 48 minutes i.e., 5 4 hrs. = { 200 * 29 } km = 40 km
5 29 5
Distance of the post-office from the village ={ 40 } = 20 km
2
Ex. 7.An aeroplane files along the four sides of a square at the speeds of 200,400,600 and 800km/hr.Find the average speed of the plane around the field.
Sol. :
Let each side of the square be x km and let the average speed of the plane around the field by y km per hour then ,
x/200+x/400+x/600+x/800=4x/y25x/25004x/yy=(2400*4/25)=384
hence average speed =384 km/hr

Ex. 8.Walking at 5 of its usual speed, a train is 10 minutes too late. Find its usual time to cover the journey.
7

Sol. :New speed =5/6 of the usual speed
New time taken=6/5 of the usual time
So,( 6/5 of the usual time )-( usual time)=10 minutes.
=>1/5 of the usual time=10 minutes.
 usual time=10 minutes
Reply

Important Note..!

If you are not satisfied with above reply ,..Please

ASK HERE

So that we will collect data for you and will made reply to the request....OR try below "QUICK REPLY" box to add a reply to this page
Popular Searches: sec schools by, algn aditya, little leaps, training for speed and distance, aditya, time of flight distance measurements using smart phones using matlab, pdf file mathematics of time and distance,

[-]
Quick Reply
Message
Type your reply to this message here.

Image Verification
Please enter the text contained within the image into the text box below it. This process is used to prevent automated spam bots.
Image Verification
(case insensitive)

Possibly Related Threads...
Thread Author Replies Views Last Post
  Statistical Algorithm for Power Transmission Lines Distance Protection seminar surveyer 0 1,118 13-10-2010, 10:57 AM
Last Post: seminar surveyer
  The Prediction Algorithm Based on Fuzzy Logic Using Time Series Data Mining Method seminar surveyer 0 1,869 13-10-2010, 10:15 AM
Last Post: seminar surveyer

Forum Jump: