Question

5. A motor car covers part of total distance with velocity
un = 10 km · h-1, the second part with velocity
and the rest with
with velocity
Uz
60 km.h-1. What is the average speed of the car?
[18 km.h -1
​

Answer 1

Answer:

18km/hr

V avg = 3v1v2v3/v1v2+v2v3+v3v1

Substitute above data without changing units

U get 18 kmphr

Answer 2

ist you need to know avg speed is Total distance/total time

In given questions it is mentioned that 2 by 5 of distance is travelled with V1 speed and 3by 5 of distance is travelled with V2 speed

You can think it as follow total distance is 5 unit and one travel 2 unit with v1 speed and 3 unit with V2 speed

toatal distance 5 unit

total time= 2/v1 + 3/v1

avg speed = 5/(2/v1 +3/v2)

= 5v1 v2/(2v2+3v1)