Two particles A and B are projected simultaneously from ground towards each other with speeds 10 m/s and52 m/s at angles 600 and 450 with horizontal from  two points separated by a distance of 15 m. They will meet after

uAx=  10 cos60o=102=5m/sec  uAy=10sin60o=1032=53m/sec uBX=uBy=52sin45o=5m/sec relative acceleration between the two is zero as acceleration aAy=aBy hence if vertical displacements are same then only they will collide sAy=uAyt  =sBy=uByt t=time of collision is same by question , uAy≠uBy hence the two particles donot collideTherefore they do not meet.