Question

If a body cover a distance x with speed v1 and then it cover another distance x with speed v2 find the average speed for the whole journey.

Answer 1

Hello !
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Average Speed = Total DIstance / Total Time 
                          = 2x                   /  x/v1 + x/v2 
                          =  2/(1/v1+1/v2)
                          = 2/(v2+v1/v1v2)
                          = 2v1v2/v1+v2
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Answer 2

Answer:

1/v1+1/v2

Explanation:

v(av)=x+x divided by x/v1+x/v2=2/v(av)=1/v1+1/v2