A  body moving along a straight line, covers  first half of its distance with uniform speed V1 and the second half of the distance with uniform speed V2 then average speed of  body is

Let us consider total distance is ‘S’ First half distance is S/2 with speedV1  Second half distance is S/2 with speed V2 average speed=total distancetotal time=St1+t2t1 is the time trave forl the distance S/2V1=S2t1           ∴t1=S2V1;   t2=S2V2   Average speed  =SS2V1+S2V2=SSV2+V12V1V2=2V1V2V1+V2