According to the equation of motion under gravity v^{2} โ u^{2} = 2gs

Where,

u = Initial velocity of the stone = 40 m/s

v = Final velocity of the stone = 0 m/s

s = Height of the stone

g = Acceleration due to gravity = โ10 ms^{โ2}

Let h be the maximum height attained by the stone.

Therefore, 0^{2} โ 40^{2} = 2(โ10)โ โ โ = {40 \times 40 \over 20} = 80 ๐

Therefore, total distance covered by the stone during its upward and downward journey = 80 + 80 = 160 m

Net displacement during its upward and downward journey = 80 + (โ80) = 0.