A car is moving on a straight road covers one third of the distance with the speed of 20 km per hour and the rest with the speed of 60 km per hour.The average speed of the car is
Answers
Let the total distance covered = x
The distance covered with speed 20 km/h = x/3
time taken to cover this distance=(x/3)/20
= x/60
Rest distance = x - x/3 = 2x/3
Distance covered with speed 60km/ h=2x/3
Time taken to cover this distance=(2x/3)/60
= x/90
Total distance = x
Total time taken = x/60 + x/90
= x/36
Average speed = (total distance)/(total time)
= (x)/(x/36)
= 36 km/h
Velocity for one third of distance V1=20Km/hr
Velocity for two third of distance V2=60Km/hr
Time taken to cover one third of distance
t1= d/3 = d/3
V1 60
Average velocity = Total distance
Total time
Vav = d = d = 30km/h
t1+t2 d/3 + 2d/3