Question

Can you please explain me that when do we use this formulae " 2×v1×v2/v1+v2

Answer 1

When the problem asks us to find the average of velocities when the distance traveled is the same, but with different velocities. look: since the pilot goes through the same distance (half of the path) with different velocities, v1 = 60 km/h and v2 = 90 km/h, the general formula for this situation is: v = 2 v 1 v 2 v 1 + v 2 ⇒ v = 2 ( 60 ) ( 90 ) 60 + 90 = 10800 150 = 72 km/h

Hope this helps you