Question

a body covers the first half of Total distance with a speed v and the second half in double the time taken for first half the average speed for whole journey is

Answer 1

Let total distance :- 2s

t1 = s/v1 ; t2 = s/v2

Avg. Speed = 2s/(s/v1 + s/v2) = 2v1v2/(v1+v2)

Answer 2

Answer:

2v/3

Explanation:

first half distance = d

another half distance = d

Total Distance = d+d = 2d

(Time = Distance/Speed)

t1 = d/v

Here, t2 is doubled,

t2=2d/v

Total Time = 3d/v

Average Speed = Total Distance/Total Time

                          = 2d/3d/v

                          = 2d*v/3d  (Here d and d will cancel)

                          = 2v/3