Please reply with solution

Let the distance between A and B is S

 

then we have v² = u²+2×a×S;

 

where a is acceleration; then we have a = (v²-u²)/(2S)

 

let v_m be the velocity at mid point; then we have v_m² = u²+2 [ (v²-u²)/(2S) ] (S/2) = ( u² + v² )/2 ;

 

hence v_m = sqrt ( ( u² + v² )/2 )