Speed, Time and distance

Basic Formula of speed and distance
Distance = Speed x Time
Speed = Distance / Time
Time = Distance / Speed
1 km. /hour =5/18 m. /sec
1 m. /sec = 18/5 km. /hour

Arjun goes to his college from his house at a speed of 3 Km / hr and return at speed of 2 km / hr. If he takes 5 hours in going and coming, the distance between his house and college is-

Average speed = (2*3*2/2+3) km / hr =12/5 km / hr.
Distance between his house and college he travelled : (12/5x 5 ) km = 12 km .

How many minutes does Seema take to cover a distance of 600 m, if she runs at speed of 40 km / hr ?

Seema speed = 40 km / hr,.
(40 x5/18) = 100/9 m / sec     (after converting it into m / sec)
So, Seema Time taken to cover 600 m = (600 x9/100) sec = 54 sec.


Harish on tour travels first 160 km at 64 km /hr and the next 160 km at 80 km /hr . The average speed of for the first 320 km of the tour  is :

Total time taken  by Harish is : = (160/64+160/8) hrs = 9/2hrs .
So that Average speed = (320 x2/9) km / hr = 71.11 km / hr

A car completes a journey in 12 hours , the first half hours complete at 23 km / hr and the second half at 25 km / hr . Find the distance?

2*12*23*25/23+25=287.5 Km   (Here formula =2 x time x S1 x S2/S1+S2)

With a uniform speed a bike covers the distance in 10 hours. When speed of bike is increased by 4 km / hr, the same distance could have been covered in 8 hours. What is the distance covered by bike?
Answer:
let the distance be x km .Then ,
x/8– x/10  = 4
x = 160 km .


A Truck covers a certain distance in 7 hours at the speed of 73 Kms/hr. What is average speed of bus? Which travels a distance of 55 Kms. less than the Truck in the same time?

Step 1 : The distance covered by the Truck = ( 73 x 7 ) = 511
Step 2 : The distance cover bus = 511 – 55 = 456 Km.
               So, average speed of the bus = = 91.2 Km/hr.


The ratio between two super fast trains is 6 : 8. if the second train runs 600 Kms in 6 hours, then what would be the speed of the first train ?

Step 1: Let the speed of two trains be 6x and 8x Km /hr.
Then, then we find the value of x,
8x =600/6 = 100
x = 100/8= 12.5.
Here, value of x is 12.5 we put in first train.
Step 2: Speed of first would be = (6 x 12.5) Km / hr =75 Km / hr.
So the Speed of First train is 75 Km / hr.

A boy without any stoppage  running on a road at an average speed of 80 km /hr , and with stoppage he covers the same distance at an average speed of 60 km / hr . How many minutes per hour does boy stop?


Time of rest per hour = ( Difference of speed/ Speed without stoppage )
 (80-60)/80=1/4 hours So, 15 minutes

A man walking at the rate of 4kmph to cover certain distance in 2hr 45 min. Running at a speed of 16.5 kmph the man will cover the same distance in what time?

 Distance = speed x Time
So, Time given = 2hr 45min = 2x 60min+ 45min= 165min
165/60=11/4
Distance =4x11/4  = 11 km
So, Time required to cover distance in speed of 16.5kmph
Time = D / S = 11 / 16.5 = 40min.



A train traveling at 90 kmph overtakes a bike traveling at 54 kmph in 30 seconds. What is the length of the train in meters?

The distance travailed by the train overtaking the bike is the same as the length of the train.
Both the object move in same direction.
So, (90 – 54) = 36kmph
convert kmph to m/sec = 36 x5/18 = 10 m / sec.
Time taken in 30 sec.
distance travailed = 10 x 30 = 300 meters.