A marble is dropped from a toy drone that is 25 m above the ground, and slowly rising with a vertical velocity of 0.8 m/s. How long does it take the marble to reach the ground?

2.18 s

Explanation:

H = - 25 m (downwards)

U = - 0.8 m/s

g = - 9.8 m/s^2

Let time taken is t.

Use second equation of motion

H = u t + 1/2 g t^2

- 25 = - 0.8 t - 1/2 * 9.8 * t^2

4.9 t^2 + 0.8 t - 25 = 0

By solving we get

t = 2.18 s