m = mass of the stone = 20 kg
g = acceleration due to gravity = 9.8 m/s²
a = acceleration of the stone in upward direction = 10 m/s²
F = applied force in upward direction
W = weight of the stone in downward direction
weight of the stone is given as
W = mg
inserting the values
W = 20 x 9.8
W = 196 N
force equation for the stone moving in upward direction is given as
F - W = ma
F - 196 = (20) (10)
F - 196 = 200
F = 396 N