The movement of skiers along the mountainside begins from a state of rest. Considering the movements as smoothly

The movement of skiers along the mountainside begins from a state of rest. Considering the movements as smoothly accelerated, determine the descent time and speed at the final descent point. Downhill acceleration 2m / s in square, descent length 80m

There is such a formula:
S = V ^ 2/2 * a
Express V. It is clear that it will be like this:
V = √2aS = √ 2 * 2 * 40 = 17.9 ms
V = a * t
We express t.
t = V / a = 17.9 / 2 = 8.95 = 9 s
Answer: t = 9 s.