friends and teachers ,,, you all gave different answers ,, so i am getting confused.
to avoid confusion ,i done this question using kinematics …
the ball raised 2m so …the velocity of the ball at the time of leaving the hand sould be

.
the hand is raised by 0.2 m . now by applying

where s=0.2m, and u=0 and v=

.
therefore a=100m/s2 . now put these values in F=ma. f=0.2X100=20N......
is there any mistake????